ARTICLE ................................... Perception of English and Catalan vowels by English and Catalan listeners: A study of reciprocal cross-linguistic similarity Juli Cebriana) Departament de Filologia Anglesa i de German!ıstica, Facultat de Filosofia i Lletres, Universitat Aut" onoma de Barcelona, Campus UAB, Bellaterra 08193, Spain ABSTRACT: This study reports the results of two experiments aimed at assessing the perceived similarity between English and Catalan vowels and diphthongs. Perceived similarity judgements were elicited from speakers of both languages involved and were compared to first language identification data from the same speakers. In experiment 1, a group of 27 naive Catalan listeners performed a perceptual assimilation task in which they were asked to identify Catalan and English vowels in terms of native categories and provide a goodness of fit rating. In experiment 2, a group of native speakers of Southern British English performed an adaptation of the same task. The results showed that most non- native vowels were consistently perceived as instances of a given native category, with varying degrees of goodness of fit. In a few cases, assimilation scores were very high in both experiments, pointing to the possibility of near- identical or shared categories. A few asymmetrical mappings were found, which were linked to the influence of language-specific cues such as the role of vowel duration in English. These results emphasize the importance of con- trasting native and non-native perception and the potential of reciprocal approaches for making predictions about non-native perception and second language development. V C 2021 Acoustical Society of America. https://doi.org/10.1121/10.0004257 (Received 13 September 2020; revised 15 March 2021; accepted 23 March 2021; published online 15 April 2021) [Editor: Megha Sundara] Pages: 2671–2685 I. INTRODUCTION assimilation of non-native phones to native categories, PAM makes a series of predictions for accuracy of discrimination of The idea that the first language (L1) phonological system non-native segmental contrasts, which PAM-L2 (Best and influences the perception of non-native sounds is widely Tyler, 2007) extends to L2 contrasts. Flege’s (1995) speech accepted. For example, the native language magnet model learning model (SLM, recently revised as the SLM-r; Flege (Kuhl and Iverson, 1995) posits that through exposure to the and Bohn, 2021) propounds that the closer a target language ambient language, speakers develop L1 sound prototypes that phone is perceived to be to a native phone, the more likely it act as perceptual magnets so that the L1 system functions as will be identified with the native category and consequently a filter through which native and non-native phones are the less likely it will be learned as a separate L2 category. perceived. Models of second language (L2) speech crucially By contrast, given enough authentic input from the target draw on the notion of cross-linguistic similarity to explain the language, a more target-like category may be established for a processes that take place in adult L2 speech acquisition and to more dissimilar L2 phone (Flege, 1995; Flege and Bohn, make predictions about the difficulty of target language 2021). What these models have in common is their reliance perception and production. Flege (1987) proposes that target on the construct of cross-linguistic similarity in order to make language phones are perceived in terms of L1 categories to predictions about categorization of L2 sounds. The notion of varying degrees through a process of equivalence classifica- phonetic similarity is in fact a key concept in the phonetics tion. L2 phones that are perceived as identical or similar to L1 sciences, as discussed below. The current paper thus aims to phones will be classified in terms of the closest L1 categories, while L2 phones that lack a clear counterpart in the L1 will contribute to our understanding of this concept by examining pattern as new phones. According to the perceptual assimila- the perception of similarity between English and Catalan vow- tion model (PAM; Best, 1995), non-native phones will be per- els by means of a novel method that evaluates the perceptual ceptually assimilated to (i.e., heard as instances of) the closest judgements of two parallel populations, namely, native native category and will be categorized as better or worse English speakers and native Catalan speakers, and contrasts exemplars of that category or be uncategorized as a L1 sound native and non-native perception. or even heard as non-speech. Based on the possible patterns of A. Measuring perceptual similarity Phonetics is concerned with the extent to which lan- a) Electronic mail: juli.cebrian@uab.cat, ORCID: 0000-0003-1547-3145. guages differ from one another in their inventories of sounds, J. Acoust. Soc. Am. 149 (4), April 2021 0001-4966/2021/149(4)/2671/15/$30.00 C 2021 Acoustical Society of America V 2671 https://doi.org/10.1121/10.0004257 and thus one of the principal questions it addresses is the distinguish between categorized and uncategorized phones, degree to which different sounds resemble each other (Bohn, the latter being non-native phones that are not perceived to 2002; Ladefoged, 1990). This question is related to the sec- have a counterpart among the L1 phonological categories. ond principle of the International Phonetic Association, The model explores whether pairs of contrasting non-native which proposes that the same phonetic symbol should be phones map onto two separate L1 categories or a single L1 used for any sound, or any similar shades of sounds, found in category (with possible varying degrees of assimilation) or more than one language (e.g., Abramson, 1988; p. 66). Bohn whether one of the two members is uncategorized. Based on (2002) underscores how the notion of phonetic similarity is the type of assimilation and the degree of cross-language crucial for a variety of areas of phonetics, including the assimilation (or perceived phonological) overlap between description of sound inventories, the development of tran- the members of each pair (i.e., overlap in the categorizations scription systems and phonetic models, and the study of lan- to native phones; Faris et al., 2018; Levy, 2009b), different guage typology and sound change, as well as for research on predictions are made for discrimination accuracy of non- language acquisition, speech errors, and automatic speech native pairs. The threshold for categorization as a L1 phone, recognition. Thus, finding a proper definition of phonetic however, varies from one study to another: 50% assimilation similarity and establishing appropriate methods for measur- as a given L1 category (Bundgaard-Nielsen et al., 2011; ing it is a basic issue not only for L2 speech research but for Faris et al., 2018), 70% (Tyler et al., 2014), or even 90% the phonetic sciences in general. (Harnsberger, 2001). The focus of this paper is not to evalu- Cross-linguistic similarity measures typically include ate the best way to quantify a categorization threshold, but articulatory descriptions, acoustic comparisons, and percep- rather to compare the perceived similarity of the sounds of tual measures [see Bohn (2002) and Strange (2007) for two languages by speakers of those two languages. One of reviews of different approaches]. Strange (2007) notes that its goals is to investigate whether some non-native sounds acoustic comparisons may be complicated by variability can be perceived as good instances of L1 categories. The caused by phonetic context, speech rate, and individual vari- approach adopted is to evaluate cross-linguistic similarity ation. Discrepancies between acoustic and perceptual mea- by contrasting the perception of L1 and non-native sounds. sures have been reported (Strange et al., 2004; Strange, In this regard, this paper follows Guion et al. (2000), who 2007). Given the difficulty of establishing appropriate propose assessing assimilation scores in light of their simi- acoustic parameters for cross-language comparisons, larity to L1 identification scores (see Sec. II C). The results researchers have advocated for perceptual measures of of previous work analyzing cross-linguistic perception of cross-language similarity, particularly when intended to Catalan and English are discussed next. assess the extent to which attunement to L1 perception influ- ences the categorization of non-native or L2 sounds (Bohn, B. Previous work on Catalan and English 2002; Flege and Bohn, 2021; Strange, 2007; Tyler, 2021; Tyler et al., 2014; among others). This study focuses on the perceived similarity between A common perceptual technique for measuring cross- Standard Southern British English (SSBE) and Catalan vow- linguistic similarity is an interlingual identification task, els. The Central or Eastern variety of Catalan has an inven- also known as perceptual assimilation task or forced choice tory of seven vowels (/i, e, E, a, O, o, u/), a reduced vowel categorization task (Baigorri et al., 2019; Best, 1995; Faris ([@]) in unstressed position, and a series of diphthongs result- et al., 2018; Strange et al., 2009; among many others). In a ing from the combination of vowels and high glides, e.g., /ai, ei, au, ou/. SSBE has a larger vowel inventory than Catalan, & perceptual assimilation task (PAT), listeners are asked to & & & consisting of 12 vowels (/i+ I E ˘+ æ ˆ A+ ` O+ U u+ @/) and eight identify exemplars of non-native phones in terms of L1 cate- gories, typically by means of labels representing the L1 diphthongs, e.g., /aI aU eI @U/.2 Figure 1 presents the vowel sounds, and to provide goodness of fit ratings. Although (monophthong) systems of Catalan and English based on the PATs are probably the most widely used tasks in studies on standard descriptions in Carbonell and Llisterri (1992) and cross-linguistic similarity, other approaches such as paired Roach (2004), respectively. comparison techniques are also found, e.g., a rated dissimi- Some previous studies have explored the perceived sim- larity task (RDT; Cebrian et al., 2011; Flege et al., 1994).1 ilarity between English and Catalan vowels. Cebrian (2006) In a RDT, listeners are presented with two stimuli and are examined the perceptual similarity between Canadian required to indicate on a (dis)similarity scale how similar English /i, I, eI, E/ and the acoustically closest Catalan coun- the two stimuli are perceived to be. terparts /i, e, ei, E/. Vowel stimuli were presented in isola- The results of these tasks are then interpreted as the tion. Catalan &speakers with little knowledge of English degree to which the non-native categories are similar to L1 perceived English /i/, /eI/, and /E/ to be closest to Catalan /i/, categories. In fact, the interpretation of the results of percep- /ei/, and /E/, respectively, about 84%–99% percent of the tual tasks is not unproblematic. The classification of non- & with goodness of fit ratings (GRs) of 4.2–6.2/7, but time, native (or L2) sounds as “new” phones or as “similar” or English /I/ obtained lower assimilation scores as Catalan /e/ “identical” to L1 phones (Flege, 1987) is not straightfor- (66%, GR: 3.5/7). These results were replicated in a later wardly defined in terms of specific assimilation scores. study involving a larger number of Catalan and Canadian PAM (Best, 1995) and PAM-L2 (Best and Tyler, 2007) English vowels and diphthongs presented in /bVs/ words 2672 J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian https://doi.org/10.1121/10.0004257 FIG. 1. Vowel systems of Catalan (Eastern variety) and English (SSBE) [based on Carbonell and Llisterri (1992) and Roach (2004), respectively]. (Cebrian, 2009), which also found that English /æ, ˆ, u, oU/ Schmidt, 2007; Strange et al., 2001; but cf. Strange et al., were strongly assimilated to L1 vowel categories (namely, 2005). In addition, the listeners in that study were experi- /a, a, u, ou/, respectively). Rallo Fabra (2005) tested two enced L2 English speakers (undergraduate English majors). & groups of Catalan learners of English varying in L2 experi- The current study differs from Cebrian et al. (2011) in the ence, a group of naive listeners and a group of undergradu- characteristics of the stimuli and in the population tested, ate students majoring in English, on their perception of made up of Catalan speakers with no experience or minimal American English vowels presented in /sVt/ words. experience with English. No previous study on Catalan and Although generally the perceptual assimilation patterns English has collected similarity judgements from SSBE were similar to previous findings, the assimilation rates native speakers. This study examines the perceived similar- obtained by Rallo Fabra were notably lower than those ity of the same set of native and non-native vowels by native reported by Cebrian (2006, 2009). This may be due to meth- speakers of the two languages involved (hence its reciprocal odological differences concerning the dialectal background nature), as discussed next. of the native speakers who provided the stimuli (speakers were from different parts of the United States), the conso- C. Reciprocal study nantal context of the vowels, and the fact that Rallo Fabra included “non-Catalan” as a possible response alternative. Cross-linguistic similarity studies typically focus on a Cebrian et al. (2011) collected perceptual similarity single population (a group of L2 learners or naive listeners), judgements from a group of 20 Catalan learners of English which is presented with a set of non-native or L2 sounds. A in an experiment that included Catalan and SSBE vowels more complete picture of the similarity relationships presented in /bVt/ words. The results of a PAT showed that between two sound systems may be achieved by eliciting the most consistent English-to-Catalan assimilation patterns, similarity judgements from two parallel populations, that is, with scores above 90% and GRs above 4.5/7, were /æ/-/a/ from speakers of the two languages being contrasted. This (100%, 4.7), /i+/-/i/ (96%, 4.6), and /E/-/E/ (91%, 4.7). bidirectional approach may also help identify cases of These were followed by /u+/-/u/ (93%, 3.8), /eI/-/ei/ (90%, phones that are possibly shared by the two languages, that & (85%, 3.5), /@U/-/ou/ (86%, 3.6), /O+/-/o/ (86%, 3.6), /ˆ/-/a/ is, cases of near-identity between native and non-native & 3.7), and /I/-/i/ (82%, 3.2) with very high scores but lower sounds. For example, Flege (1992) suggests that to know GRs. Finally, the assimilation patterns were least consistent whether a non-native sound is perceived to be indistinguish- with /A+/-/a/ (70% and 2.5, while /A+/-/O/ reached 20% and able from a native category, this non-native phone should be 3.9), /`/-/O/ (70% and 4.1, with 28% and 4.4 for /`/-/o/), and undetectable when produced in a native context. Further, a English /˘+/, which did not find a match in the L1 (as /e/ reciprocal approach can help evaluate to what extent percep- 30%, 2.0; as /E/ 24%, 1.7; as /a/ 23%, 1.4, and as /o/ and /O/ tual distance is a shared construct by speakers of the two 9% and 2.1–2.7). Hence, the findings in Cebrian et al. languages involved, that is, an intrinsic characteristic of the (2011) showed that some English vowels were perceived as sounds that are contrasted, or if it is influenced by the way being very similar to native categories, a few more were sounds are organized in each of the languages involved. To consistently mapped onto a L1 category but judged as worse our knowledge, no previous research has looked at cross- fitting, and a subset were perceived as not having a clear linguistic perceived similarity with reciprocal populations in counterpart in the L1, particularly English /˘+/. However, the same study, particularly involving vowels. the stimuli used in the experiments were unmodified /bVt/ The only prior research is a set of two studies on cross- words, and it is possible that differences in the prevoicing of linguistic perception of consonants by Korean (Schmidt, the /b/ and the release (and aspiration) of the /t/ may have 1996) and English (Schmidt, 2007) speakers. Schmidt found influenced the listeners’ similarity judgements. Consonantal evidence of parallel cross-linguistic mappings emphasizing context has been found to affect perception of vowel simi- the perceived similarity between the native and non-native larity (Bohn and Steinlen, 2003; Levy, 2009a, 2009b; sounds. However, she also found that cross-linguistic J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian 2673 https://doi.org/10.1121/10.0004257 similarity varied for the two language groups, depending on instruction is typically grammar and vocabulary rather than context-specific cues such as amount of labialization of the pronunciation and perception. Thus, their familiarity with following vowel, variations in voice-onset time (VOT), and the English vowel system was considered minimal. None of the presence of burst-like transitions in nasals. Schmidt con- the Catalan participants had spent more than 1 month in an cluded that “reciprocal studies…can delineate the relation- English-speaking country. For these reasons, the participants ship between sounds in two languages, as well as the cues can be considered naive listeners (Best and Tyler, 2007). All used by speakers of each language so that more accurate participants reported normal hearing and were compensated predictions about cross-linguistic speech perception can be for their participation. formulated” (Schmidt, 2007; pp. 199–200). With these argu- ments in mind, the current study assesses cross-linguistic 2. Stimuli perceived similarity by testing native speakers of the two The stimuli consisted of 13 SSBE and 11 Catalan languages examined. vowels and diphthongs. The Catalan vowels were the seven monophthongs /i e E a O o u/. The reduced vowel ([@]) was D. Aims not included, as it only appears in unstressed position in This study aims to contribute to our general understand- Eastern Catalan and is subject to large contextual variability ing of the concept of phonetic similarity by evaluating a (Recasens, 2014). In addition, four rising diphthongs, novel method of measuring cross-linguistic similarity that namely, /ei ou ai au /, were also included. To limit the com- involves (a) comparing the perceptual evaluation of native plexity and& duration & & & of the task, only a subset of all possible and non-native sounds and (b) contrasting the perceptual Catalan rising diphthongs, i.e., combinations of a monoph- judgements of two parallel populations, naive listeners of thong and a semivowel (/i / or /u /), were used. The selected the two languages involved. The study also investigates to diphthongs were the ones&that had & been found to be percep- what extent cross-linguistic perceived similarity is affected tually closest to English vowels in previous studies involv- by the characteristics of the sound systems evaluated. The ing Catalan and English (Cebrian, 2009; Cebrian et al., global objective is to assess the similarity of a near- 2011). The English stimuli contained the vowels and diph- complete set of Catalan and English vowels and diphthongs thongs /i+ I E æ aI aU ˆ A+ ` O u+ eI @U/ (the English vowels to be able to predict areas of difficulty in the perception and /˘+/ and /U/ were excluded from the PAT, as previous studies production of L2 vowels for adult L2 learners and to evalu- have shown that these vowels are not consistently assimi- ate whether there are (perceptually) near-identical cross-lin- lated to any single Catalan vowel and this paper explores the guistic categories, that is, if there are non-native phones that prevalence of reciprocal cross-linguistic mappings).3 The can be considered acceptable exemplars of native catego- vowels were elicited in /b/ þ vowel þ /t/ sequences, which ries. The results of two experiments are presented. In the is a possible sequence in both languages. To elicit these first experiment, a group of native Catalan speakers assessed sequences, the /bVt/ words were embedded in a carrier the perceived similarity between Catalan and English vow- phrase that included a rhyming real word, as the /bVt/ con- els by means of a PAT. In the second experiment, an adapta- text created some non-words particularly in Catalan. The tion of the same task was administered to a group of English English and Catalan carrier phrases were “It rhymes with native speakers. hot. I say bot. I say bot again,” and “Rima amb dit. Ara dic bit. Ara dic bit un cop,” respectively. Each English speaker II. EXPERIMENT 1: PERCEIVED SIMILARITY OF SSBE recorded six repetitions of the phrases with the words beat VOWELS BY CATALAN SPEAKERS /i+/, bit /I/, bet /E/, bat /æ/, but /ˆ/, Bart /A+/, bot /`/, bought A. Methodology /O+/, boot /u+/, bait /eI/, boat /@U/, bite /aI/, and bout /aU/, at a comfortable pace and with falling intonation. The order of 1. Participants the carrier phrases was randomized in each repetition. The The participants were 27 Catalan-dominant Catalan- Catalan words were elicited in the same fashion. The Spanish bilinguals (15 females) selected from a pool of 38 Catalan sequences were bat /a/, b!et /e/, bèt /E/, bit /i/, b!ot /o/, potential participants on the basis of their responses to a per- b"ot /O/, but /u/, bait /ai /, beit /ei /, baut /au /, and bout /ou /. sonal and linguistic background questionnaire. Selected par- & Stimuli were elicited from & three male& native speakers & ticipants were born to Catalan-speaking parents, lived in per language. The SSBE speakers (mean age: 35, range Catalan-speaking homes, and reported using Catalan 29–44) had spent most of their lives in the South of 75%–100% of the time. Their average age was 24, ranging England. They were recorded in a soundproof booth at the from 17 to 48. Most participants were undergraduate stu- research laboratory at University College London. The dents. The ideal participants would be speakers with little or Catalan speakers were Catalan-dominant Catalan-Spanish no knowledge of the non-native language in the experiment. bilinguals living in Barcelona and neighbouring areas (mean While this was not a problem for the English subjects in age: 30, range: 21–35). They were selected on the grounds experiment 2, it was more difficult to accomplish with the of a language use questionnaire and a short interview with a Catalan participants. Most had studied English as a foreign phonetically trained Catalan researcher. Catalan recordings language (EFL) at school. However, the focus of EFL were made in a sound-attenuated room at EUPMt technical 2674 J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian https://doi.org/10.1121/10.0004257 university (Escola Universit"aria Politècnica de Matar!o, Neighbouring sounds have been found to affect percep- Matar! o, Barcelona). Recordings were made with a digital tual assimilation judgements (Bohn and Steinlen, 2003; recorder [Marantz (Kanagawa, Japan) PMD660] and a uni- Levy, 2009a, 2009b; Schmidt, 2007). In addition, English directional dynamic microphone [Shure (Niles, IL) SM58]. and Catalan differ in the amount of prevoicing of word- The recordings were digitized at a 44 kHz sampling rate, initial voiced stops (typically around 0 ms or short-lag VOT and the stimuli were normalized for intensity (70 dB). The for English, voice lead for Catalan voiced stops). best two tokens per talker and language were selected, based Consequently, stimuli were edited to include from the on auditory judgements and spectrographic analyses. Figure release of the /b/ until the end of the vowel portion and 2 displays the distribution of the English and Catalan vowel beginning of the /t/ closure. Thus, the portion corresponding stimuli in a F1 " F2 (first and second formant) space, aver- to the /b/ closure and the release of the /t/ were excluded aged across the three male speakers for each language while maintaining intact the cues to the vowel. [Lobanov’s (1971) speaker normalization method was applied to the formant data; see Adank et al. (2004) for a discussion of normalization methods]. The F1 and F2 of 3. PAT every vowel stimulus were measured from a 50-ms window In this task, listeners heard Catalan and English vowel located manually at a steady-state portion between one-third stimuli presented in a random order and had to identify each and two-fourths into the vowel, using PRAAT (Boersma and stimulus as one of several possible L1 categories and then Weenink, 2018). The resulting measurements were in accor- provide a goodness of fit rating on a seven-point scale, dance with reported values for male speakers of SSBE where 1 meant a bad exemplar of the chosen vowel and 7 (Deterding, 1997; Ferragne and Pellegrino, 2010) and meant a good, i.e., native-like, example. Both L1 and non- Eastern Catalan (Recasens and Espinosa, 2006; Recasens, native vowels were included in the PAT so that the tasks 2014). Among the front vowels, some Catalan (C) and used with Catalan speakers and English speakers were as English (E) vowels appear to be acoustically very similar, similar as possible. Crucially, the native perception data namely, the low vowels C /a/ and E /æ/ and the mid front were used as a baseline for comparison (e.g., Cebrian, 2006; vowels C /E/ and E /E/, followed by C /i/ and E /i+/ and C /e/ Escudero and Chl!adkov!a, 2010; Guion et al., 2000). Further, and E /I/. Regarding the back vowels, the plot indicates a including L1 sounds facilitates the assessment of whether less clear pattern of acoustic mappings, with C /O/ and E /A+/ participants understood the instructions and used the having the greatest similarity. English /u/ appears to be nota- response categories correctly. bly fronted, in agreement with previous descriptions Although some studies propose including all possible (Ferragne and Pellegrino, 2010; Harrington et al., 2008). L1 categories as response options in PATs (e.g., Bundgaard- Diphthongs were measured at two different points, roughly Nielsen et al., 2011), a decision was made to divide the PAT 25% and 75% into the vowel, and presented expected values into two smaller tasks, each with a subset of the possible L1 in relation to the location of the monophthongs. Finally, the responses. This was motivated by the fact the inclusion of duration of the Catalan vowels ranged from 129 ms (/i/) to 11 Catalan vowels and 13 English vowels in a single task 229 ms (/ou/), showing the expected increase in duration resulted in a very large number of stimuli, prone to fatigue from high to& low vowels (e.g., Recasens, 2014), and diph- effects. In addition, previous studies provide information thongs were longer than monophthongs. English vowel concerning what L1 options are more often selected for each duration ranged from 136 ms for /I/ to 258 ms for /A+/, with non-native vowel (e.g., Cebrian et al., 2011; Rallo Fabra, tense vowels being overall longer than lax vowels. 2005). Thus, the stimuli were divided into two sets: set A involved mostly front vowels (English /aI, æ, eI, E, I, i+, ˆ/ and Catalan /ai, a, ei, E, e, i/), and set B consisted of mostly back and rounded & vowels & (English /aU, æ, `, O+, @U, u+, A+/ and Catalan /au, a, O, o, ou, u/). Two tokens of each vowel produced by each & of the &three talkers were included. The non-native tokens were repeated twice, while the native tokens were presented once. To have balanced sets, the English vowel /æ/ and the Catalan vowel /a/ appeared in both sets, and each token was presented only once in each set. The total number of trials in each task was 114, 78 involving non-native (English) vowels and 36 L1 Catalan vowels. The response alternatives consisted of high fre- quency keywords representing each of the L1 sounds. The response labels for set A were xai (for /ai /), gat (/a/), rei & (/ei /), set (/E/), fet (/e/), and dit (/i/), meaning sheep, cat, FIG. 2. Normalized F1 " F2 values of each of the English (E) and Catalan & (C) vowel stimuli, averaged across three male speakers of each language. king, seven, fact, and finger, respectively. In the case of set The Lobanov transformation has been used (Lobanov, 1971). B, the response options were gat (/a/), dau (/au/), got (/O/), J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian 2675 https://doi.org/10.1121/10.0004257 mot (/o/), pou (/ou/), and mut (/u/), meaning cat, dice, drink- perception as well as when contrasting results across & ing glass, word, water well, and mute.4 experiments. The average correct identification of the Catalan vowels 4. Procedure was 92% (range 80%–100%), with an average rating of 5.9 and a mean fit index score of 5.4. These identification per- The order of the two sets (A and B) was counterbal- centages are within what has been found in comparable pre- anced across all listeners. Instructions were given at the vious studies reporting L1 vowel identification [94.8% in beginning of the experiment. Listeners were encouraged to Cebrian (2006) for Catalan vowels, with an average GR of use the whole range of the scale. The listeners performed 5.7/7; 95% (range 78%–99%) and 95.6% for Spanish vowels the tasks individually in a soundproof room. They listened in Cebrian (2019) and Escudero and Chl!adkov!a (2010), to the stimuli over headphones [Sennheiser (Wedemark, respectively]. The L1 vowels /e/ and /o/ obtained the lowest Germany) HD-25] and responded by clicking on one of the identification scores, 80% in both cases. The front vowel /e/ responses appearing on the computer screen. There was no was misidentified as /i/ 13% and as /E/ 7% of the time, while time limit for the responses, and each stimulus could be /o/ was misidentified as /O/ 19% of the time. Other misiden- replayed once if necessary, but participants were encouraged tification percentages were /E/ as /e/ and /O/ as /o/ (10%) and to respond based on their immediate impressions. There was /u/ as /o/ (7%). These patterns of misidentification may a possibility for a short pause every 24 trials. PRAAT software reflect a possible lower degree of phonetic or perceptual sta- (Boersma and Weenink, 2018) was used to conduct the bility of the mid vowel pairs in contrast with more periph- experiments. The experimental task was preceded by a short eral vowels (e.g., Mora and Nadeu, 2012). practice phase to familiarize participants with the range of The crucial stimuli in the experiment were the non- possible identification and rating responses. The practice native vowels. Recall that the order of presentation of the session consisted of 12 trials (6 native and 6 non-native tasks, front vowels (set A) first or back vowels (set B) first, vowels). The participants took on average 20–30 min to was counterbalanced among participants. Despite some vari- complete both sets of the PAT. The participants in this study ability across individuals, the modal responses were the performed another perceptual task after the PAT, whose same regardless of task order in all cases with one excep- results are not reported in this paper. tion: for the subgroup who performed task B first, the English vowel /A+/ (set B) was most frequently assimilated B. Results to Catalan /O/ (69% of the time), followed by /a/ (16%), The percentage of times each L1 and non-native stimu- while for those who performed task B second, /A+/ was more lus were identified as each of the L1 response categories and frequently assimilated to /a/ (47%), followed by assimila- the mean GRs for each were calculated.5 This analysis pro- tions to /O/ (39%). An inspection of the individual data indi- vided the correct identification scores for Catalan vowels cated that the perceptual assimilation of English /A+/ was and modal assimilation scores (most frequent identification subject to both between-subject and within-subject variabil- as a L1 vowel) for each non-native vowel. Table I shows the ity: while some participants tended to chose one of the identification accuracy of each of the L1 vowels, the GR responses (/O/, /a/, or /au/), roughly half of the participants & (equally distributed between the two task orders) provided received, and the fit index score, a composite score that combines the two previous measures by multiplying the inconsistent responses. To assess whether task order (AB vs identification proportion by the goodness of fit rating (Guion BA) could have influenced the results, Mann–Whitney U- et al., 2000; Lengeris, 2009; among others).6 The fit index tests were conducted on the percent identification/assimila- score will be used when comparing native and non-native tion as the modal response and on the corresponding GRs. The results yielded no significant difference between the TABLE I. Identification accuracy, GRs, and FIs for L1 Catalan vowels. results of the participants who performed set A followed by set B and those who performed the tasks in the opposite Catalan Correct identification Rating FI order (% identification/assimilation: U ¼ 359, p ¼ 0.145; vowel (%) (out of 7) (maximum 7) GR: U ¼ 310, p ¼ 0.657). The results were thus collapsed /i/ 100 6.3 6.3 across task orders. /a/ 99 5.9 5.9 The variability in the responses for /A+/ underscores the /au/ 99 5.9 5.9 fact that individuals sharing the same L1 may differ in the & /ai / 98 5.8 5.7 categorization of non-native vowels (Faris et al., 2018; & /ei / & 93 5.5 5.1 Gilichinskaya and Strange, 2010; Strange et al., 2009; Tyler /u/ 93 6.1 5.7 et al., 2014). Given this variability, for each non-native /ou/ 92 5.6 5.2 vowel, the number of participants who selected a given & /E/ 90 6 5.3 response at a consistent rate was tallied, following Strange /O/ 86 6 5.2 et al. (2009) and Gilichinskaya and Strange (2010). This /o/ 80 5.7 4.6 /e/ 80 5.6 4.5 measure provides information about the consistency with Means 92 5.9 5.4 which a given target vowel was assimilated to a L1 cate- gory. As discussed above, studies vary in the percent 2676 J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian https://doi.org/10.1121/10.0004257 assimilation considered as the categorization threshold. We assimilation scores of 76% or higher, including six cases are not concerned in this paper with establishing the most reaching 87% and higher. Thus, most SSBE vowels were appropriate threshold, but rather with assessing the degree categorized in terms of L1 categories, assuming a categori- of consistency across listeners. For that purpose, the 70% zation threshold of 70% (Tyler et al., 2014). The exception (Tyler et al., 2014) and 50% (Faris et al., 2018; Bundgaard- was English /A+/, perceived as Catalan /O/ and /a/ 54% Nielsen et al., 2011) cutoffs are reported. The results are and 31% of the time, respectively, qualifying as the most presented in Table II, following a decreasing order of assim- dissimilar from a Catalan vowel (probably in addition to ilation scores. Only modal responses and assimilation scores English /˘+/ and /U/; see Footnote 3). above chance are provided. The full set of responses is pro- The outcome of the current experiment in fact follows vided in a confusion matrix in the Appendix (see Table V). the general trends reported by Cebrian et al. (2011), which The English vowels /æ aU ˆ aI E i+/ were the most con- also looked at British English and Catalan vowels. The three sistently assimilated to a Catalan category, both in terms of SSBE vowels that received the highest assimilation scores assimilation rates (91–99%) and agreement across partici- and goodness ratings in Cebrian et al. (2011), namely, /i+ E æ/ pants (22–27). The GRs varied, however, ranging from /aI/’s as Catalan /i E a/, respectively, also received the highest comparatively lower rating as /ai/ (3.6) to the highest rating scores in the current study. In general, the pattern of modal received by English /æ/ and /E/ &(5.6) as Catalan /a/ and /E/, responses was highly consistent across both studies. This respectively. Both English /æ/ and /ˆ/ were consistently was not unexpected, as the stimuli in both studies involved mapped onto the same L1 vowel, /a/, but the former received bVt words, although in the current study, neighbouring con- higher goodness ratings than the latter (5.5 vs 4.6). The vowels sonants were edited to allow listeners to focus on the vowels /` u+ I @U O+ eI/ reached assimilation percentages between (see Sec. II A 2). However, the two studies obtained differ- 76% and 82% with GRs ranging from 3.7 to 5.6, while the low ent results for /A+/ and /I/. The modal response for E /A+/ in vowel /A+/ revealed the least consistent pattern, being identified Cebrian et al. (2011) was C /a/ (78%; GR: 2.5), followed by mostly with Catalan /O/ (54%), followed by /a/ (31%). This C /O/ (20%; GR: 3.9), as opposed to C /O/ (54%, GR: 4.8) and C /a/ (31, GR: 3.9) in the current experiment. The dis- vowel displayed the greatest amount of variability in responses crepancy may be in part related to the amount of variability among participants. across participants observed for this vowel, as can be C. Discussion observed by the comparatively small number of participants who consistently assimilated E /A+/ to either C /O/ or /a/, as Experiment 1 examined the perceived similarity mentioned above. The discrepancy is even greater with between Catalan and SSBE vowels from the perspective of respect to E /I/. Cebrian et al. (2011) report that /I/ was Catalan-speaking listeners. The results for the native assimilated to C /i/ 82% of the time and to C /e/ 15% of the Catalan stimuli showed that the Catalan listeners were able time, both with similar GRs (3.4–3.5). In the current study, to identify L1 vowels accurately and consistently, within the the modal response was C /e/ (80%, vs 12% as /i/), with ranges of what is generally found in L1 perception studies. higher GRs (5.6 as /e/, 3.8 as /i/). In addition to the differ- Regarding the non-native vowels, most English vowels ence between the two studies concerning the neighbouring show a consistently identified counterpart in the L1, with consonants, the studies also differed in the population [naive TABLE II. Perceived similarity between non-native (English) vowels and L1 (Catalan) vowels. No. of Ss assim. $ 70%/50% ¼ number of subjects who selected a given response 70%/50% of the time or more. The total number of participants was 27. Modal responses appear in boldface. Assimilations below chance level (16.7%) have been excluded. English target V L1 response Assimilation (%) GR FI No. of Ss assim. $ 70% No. of Ss assim. $ 50% /æ/ /a/ 99 5.6 5.5 27 27 /aU/ /au/ 99 4.9 4.9 27 27 & /ˆ/ /a/ 98 4.7 4.6 27 27 /aI/ /ai/ 95 3.6 3.4 26 26 & /E/ /E/ 91 5.6 5.1 25 26 /i+/ /i/ 87 5.7 5.0 22 27 /`/ /O/ 82 5 4.1 20 26 /u+/ /u/ 82 3.7 3.0 22 25 /I/ /e/ 80 5.6 4.5 20 24 /@U/ /ou/ 79 3.7 2.9 22 24 & /au/ 19 2.6 0.5 2 3 /O+/ /o/ 77 4.8 3.7 19 25 /eI/ /ei/ 76 4.2 3.2 12 27 & /ai/ 21 4.3 0.9 & /A+/ /O/ 54 4.8 2.6 8 16 /a/ 31 3.9 1.2 3 9 J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian 2677 https://doi.org/10.1121/10.0004257 listeners in the current study vs L2 English speakers in /ou/-/@U/, /ei/-/eI/, /O/-/`/, /O/-/A+/), despite assimilation per- Cebrian et al. (2011)]. Interestingly, Rallo Fabra (2005) & centages & 76%, reaching 95% in the case of /ai/-/aI/. above found that a group of inexperienced Catalan listeners identi- Differences in articulation such as the fronted nature & of fied American English /I/ most often as C /e/ (63%), fol- SSBE /u+/, particularly in alveolar context (e.g., Harrington lowed by /E/ (19%) and /i/ (16%), while an experienced et al., 2008; Levy, 2009a), or central beginning of the diph- group (undergraduate students in an English Studies degree) thong /@U/ may account for the low ratings. One of the goals was found to provide less consistent results (40% as /i/, 12% of this paper is to assess whether the Catalan-English simi- as /e/, 12% as /E/, and 36% as “non-Catalan”). The lack of larity judgements will be replicated when evaluating the per- consistency across studies regarding the assimilation of E /I/ ception of English native speakers. This is explored in to C /e/ or /i/ may be related to the fact that Catalan /e/ is experiment 2. perceptually less stable (e.g., Mora and Nadeu, 2012), as illustrated by its lower L1 identification scores (see Table I), III. EXPERIMENT 2: PERCEIVED SIMILARITY OF and to cross-study methodological differences in population, CATALAN VOWELS BY ENGLISH SPEAKERS variety of English, phonetic context of the stimuli, and A. Methodology response options used. Still, the results tend to indicate that English /I/ is perceptually closest to Catalan /e/, particularly 1. Participants for naive listeners, and that the degree of assimilation Twenty-seven native speakers of SSBE participated in observed with /I/ is weaker than with other non-native to the experiment (23 females). They were undergraduate (19) native assimilations. The results of the current study are and graduate (8) students in the Division of Psychology and generally in agreement with previous studies and probably Language Sciences at University College London. They had present the most reliable account of Catalan-SSBE percep- all acquired English as a first language and had been raised tual similarity, given the inclusion of a large number of in Southern England or had been born to parents from vowels, the nature of the stimuli, and the choice of naive Southern England. Most spoke no other language fluently listeners. except for one participant who was fluent in German. One One of the goals of this study was to examine how simi- participant reported having some knowledge of Spanish but lar native and non-native vowels may be perceived to be. To was not fluent. Their average age was 22, ranging from 18 that effect, the results for L1 identification and non-native to to 30. All participants reported normal hearing and were L1 assimilation can be compared by comparing cross- paid for their participation. linguistic assimilation patterns with L1 vowel identification values. Guion et al. (2000) propose that non-native phones 2. Stimuli that fall within 1 standard deviation of the mean fit index (FI) obtained for the L1 phones can be considered “good” The stimuli were the same as in experiment 1. exemplars of that L1 category, while those non-native phones whose FIs fall within 1–2 standard deviations of the 3. PAT native mean value can be regarded as “fair” matches. The The design of the PAT followed the same structure as average FI score for L1 Catalan vowels was 5.4 (ranging in experiment 1 and involved the same stimuli. There was from 4.5 to 6.3), and the standard deviation was 0.6. Thus, one task for front vowels (set A) and one for back vowels English vowels with FIs of 4.8 (i.e., 5.4 % 0.6 ¼ 4.8) or (set B), and both tasks included non-native (Catalan) and L1 higher can be considered good matches to the L1 vowels (English) stimuli, in the same fashion as was done for exper- they are assimilated to. A few mappings fall within this iment 1 (see Sec. II A 3). The total number of trials per task range, namely, E /æ/ as C /a/ (FI¼5.5), E /E/ as C /E/ (5.1), (A and B) was 108 (66 Catalan and 42 English stimuli). The E /i+/ as C /i/ (5), and E /aU/ as C /au/ (4.9). English vowels response alternatives in this case were bat/hat, bite/light, & that patterned as a fair match to L1 Catalan vowels had a FI bait/hate, bet/set, bit/hit, beat/heat, but/hut, and Bart/art for between 4.3 and 4.7 (i.e., 5.4 % 2 " 0. 6 ¼ 4.2). These were set A and bat/hat, about/gout, bot/hot, bought/sort, boat/ E /ˆ/ as C /a/ (4.6) and E /I/ as C /e/. All remaining modal goat, boot/hoot, but/hut, and Bart/art for set B. assimilations patterned as poor matches, including E /aI/ as C / ai/, with a high assimilation score (95%) but low GR (3.6) and 4. Procedure & consequently a low FI (3.4). The rest of the poorly assimilated The procedure for experiment 2 was the same as the English vowels had identification scores of 82% or lower one described for experiment 1 in Sec. II A 4. and FI of 4.1 (E /`/ as C /O/), 3.7 (E /O+/ as C /o/), 3.2 (E /eI/ as C /ei/), 3 (E /u+/ as C /u/), 2.9 (E /@U/ as C /ou/), and the lowest & 2.6 obtained by E /A+/ as C /O/. & B. Results being In brief, the results of experiment 1 show that most The percentage of correct identification of the L1 English vowels are readily assimilated to L1 Catalan catego- English vowels and the corresponding average GRs and FIs ries, yielding a number of good (C-E /au/-/aU/, /E/-/E/, /a/-/æ/, are given in Table III. The average identification accuracy /i/-/i+/) and fair matches (C-E /e/-/I/ & and /a/-/ˆ/). The was 92% (range 76%–100%), with average GRs and FIs of remaining were poor matches (C-E /ai/-/aI/, /u/-/u+/, /o/-/O+/, 6.1 and 5.7 out of 7, respectively. These results are very & 2678 J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian https://doi.org/10.1121/10.0004257 TABLE III. Identification accuracy, GRs, and FIs for L1 English vowels. level, the average GR, FI, and the number of participants who selected the modal response 70% and 50% of the time English Correct identification Rating FI vowel (%) (out of 7) (maximum 7) or more (see Table VI in the Appendix for the complete range of responses). The modal responses were the same for /aI/ 100 6.3 6.3 the group who performed set A followed by set B and those /u+/ 100 6.6 6.6 who performed the tasks in the opposite order, and the /@U/ 99 6.6 6.6 results of Mann–Whitney U-tests conducted on the percent /æ/ 98 6.4 6.3 /i+/ 97 5.7 5.5 identification/assimilation as the modal response and on the /aU/ 96 6.2 6 corresponding GR confirmed there was no significant effect /O+/ 95 6.2 5.9 of task order (% identification/assimilation: U ¼ 340, /eI/ 93 6 5.6 p ¼ 0.971; GR: U ¼ 370, p ¼ 0.552). /E/ 92 5.8 5.3 The Catalan vowels and diphthongs /ou, ei, au, E, ai/ /A+/ 89 6.3 5.6 were consistently assimilated to the English &vowels & &/@U, eI, & /I/ 83 5.9 4.9 aU, E, aI/, respectively, with assimilation scores equal to or /ˆ/ 80 6.2 4.9 higher than 90% (90%–97%), GR between 4.9 and 5.4 out /`/ 76 5.2 4 of 7, and a high degree of agreement among English listen- Means 92 6.1 5.7 ers (24–27 participants selected the modal response at least 70% of the time). Catalan /a/ reached 86% identification as English /æ/ with a GR of 5.3. Catalan /e/ and /u/ were similar to the L1 Catalan identification scores obtained in mapped onto English /I/ and /u+/ (73% and 70%, GR 5 and experiment 1 and are within the range of what has been 4.1, respectively). Three Catalan vowels did not reach a reported in previous studies involving English vowels, e.g., 70% threshold for categorization: Catalan /i/, split between 95% (range: 82%–99.6%) in Hillenbrand et al. (1995) and English /i+/ (62%, GR: 4.5) and /I/ (37%, GR: 4.3), and 89% (range: 75%–100%) in Rallo Fabra and Romero (2012) Catalan /o/ and /O/, which obtained the lowest assimilation for American English vowels. Most English vowels rates, both being predominantly perceived as English /`/ obtained identification scores higher than 90% and GRs (59% and 53%, GR: 4.4 and 5, respectively) and then as /O+/ close to 6 or higher. The English vowels that obtained the (18% and 33%) and /ˆ/ (12% and 9%). lowest identification percentages were /I, ˆ, `/ (83, 80, and 76%, respectively), and the most common misidentifications C. Discussion were /I/ as /E/ (14%), /ˆ/ as /æ/ (13%) or /A+/ (7%), and /`/ as /A+/ (11%), /O+/ (8%), or /ˆ/ (5%). It is possible that these The perceptual similarity between Catalan and SSBE vowels may have posed a greater challenge to native listen- vowels from the perspective of native English speakers was ers as they are lax vowels, shorter in duration than the rest examined in experiment 2 by means of a PAT using the of the vowels, and typically followed by an audible conso- same stimuli as in experiment 1, adapted to native English nant in the coda. listeners. Regarding L1 perception, English listeners were Table IV presents the modal responses for each of the overall successful identifying the native vowels, with a Catalan target vowels in decreasing order of assimilation mean accuracy of 92%, within the average identification scores, as well as other assimilation patterns above chance scores reported in the literature for native English vowels. TABLE IV. Perceived similarity between non-native (Catalan) vowels and L1 (English) vowels. No. of Ss assim. $ 70%/50% ¼ number of subjects who selected a given response 70%/50% of the time or more. The total number of participants was 27. Modal responses appear in boldface. Assimilations below chance level (12.5%) have been excluded. Catalan V L1 response Assimilation (%) GR FI No. of Ss 70% (N ¼ 27) No. of Ss 50% (N ¼ 27) /ou/ /@U/ 97 5 4.8 27 27 & /au/ /aU/ 94 5.4 5.1 26 26 & /ei/ /eI/ 94 5 4.7 25 26 & /E/ /E/ 92 4.9 4.5 25 27 /ai/ /aI/ 91 5.2 4.7 24 25 & /a/ /æ/ 86 5.3 4.5 19 26 /e/ /I/ 73 5 3.7 16 22 /u/ /u+/ 70 4.1 2.9 16 21 /i/ /i+/ 62 4.5 2.8 14 18 /I/ 37 4.3 1.6 6 9 /o/ /`/ 59 4.4 2.6 11 16 /O+/ 18 3.8 0.7 1 5 /O/ /`/ 53 5 2.6 7 14 /O+/ 33 4.3 1.4 1 9 J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian 2679 https://doi.org/10.1121/10.0004257 The lower scores obtained by some lax vowels are possibly assimilation scores under 70%, and in both cases, the modal due to the added difficulty of identifying lax vowels in response was English /`/. Despite the presence of available isolation. native categories in the low and mid back vowel space (/A+, As was observed with the Catalan listeners, a relatively `, O+/), the two Catalan back rounded vowels were perceived consistent pattern of modal responses was found in the as instances of the same L1 category /`/. Vowel duration English listeners’ perception of Catalan vowels. Six of the may have played a role in this case too. SSBE /O:/ is consider- 11 vowels and diphthongs tested reached assimilation scores ably longer than /`/, while the two Catalan vowels are similar between 86% and 99%, two more vowels were just around in duration and closer to the English short vowel. The dura- the 70% categorization threshold, and three vowels were tion of the stimuli reflects this pattern: C /O/: 174 ms, C /o/: under 70% (53%–62%). As was done in experiment 1, to 148 ms, E /`/: 156 ms, E /O+/: 245 ms. Hillenbrand et al. explore the extent to which the non-native vowels patterned (2000) report that while native (American) English speakers as possible instances of L1 categories, the L1 identification predominantly rely on spectral differences, they may attend scores and non-native vowel assimilation scores were com- to duration as a cue to vowel identity, particularly in the pared in terms of fit index scores, following Guion et al. case of mid and low vowels. The comparatively short duration (2000). The average FI for L1 English vowels was 5.7 (rang- of C /o/ may have made it an unlikely match for E /O+/, ing from 4 to 6.6), and the standard deviation was 0.75. prompting a preference for a lower, shorter, vowel, i.e., E /`/. Therefore, in this case, non-native vowels with FIs of 4.9 In any case, the Catalan /o/-/O/ contrast emerges as the most (i.e., 5.7 % 0.8 ¼ 4.9) or higher were classified as good difficult for English speakers to learn, in terms of their assimi- instances of the L1 vowels. Only one Catalan phone quali- lation to the same native category and the relatively low assim- fied as such, namely, C /au/ as E /aU/ (5.1). Five Catalan ilation scores and FIs. The comparison of the results of the two & vowels patterned as fair matches, i.e., within 2 standard experiments is discussed in Sec. IV. deviations of the L1 identification mean, that is, between 4.1 and 4.9 (5.7 % 2 " 0.8 ¼ 4.1). These were C /ou/ as E /@U/ IV. GENERAL DISCUSSION AND CONCLUSIONS (4.8), C /ei/ as E /eI/ (4.7), C /ai/ as E /aI/ (4.7),& C /E/ as E & C /a/ as E /æ/ (4.5). /E/ (4.5), and & The rest of the vowels This study has investigated the perceived similarity obtained FI lower than 4.1 and, in fact, were also the vowels between Catalan and English vowels and diphthongs by with the lowest assimilation scores (73%–53%): C /e/ as eliciting similarity judgements from 27 naive native speak- E /I/ (3.7), C /u/ as E /u+/ (2.9), C /i/ as E /i+/ (2.8), and both ers of each language. The participants performed a PAT in C /o/ and C /O/ as E /`/ (2.6). which native and non-native exemplars were identified in The results of the second experiment indicate that a terms of native categories and rated for goodness of fit to number of Catalan vowels were readily assimilated to native that category. The results for the native vowels were highly English categories, particularly the C-E pair /au/-/aU/, quali- comparable across experiments, showing high levels of fying as a good match, and the C-E pairs /ou/-/@U/, & /ei/-/eI/, accuracy (92%) and high goodness ratings. Catalan mid & & /ai/-/aI/, /E/-/E/, and /a/-/æ/ that patterned as fair matches. vowels and English lax vowels obtained somewhat lower & The assimilation scores for Catalan /e/ and /u/ as English /I/ identification rates, which can be linked to their more unsta- and /u+/, respectively, barely reached the categorization ble perceptual nature and difficulty of perceiving vowels in threshold of 70% and qualified as poor matches. isolation. Still, the overall rates of identification were high Articulatory differences may account for /u/’s lower scores, and comparable to previous L1 perception studies. as discussed above. In addition, English listeners identified The L1 identification results served as the basis for Catalan /u/ as English /ˆ/ 12% of the time. It is possible that interpreting the assimilation scores obtained by the non- in these cases, the desired response was English /U/, but the native vowels. The results of both experiments showed that absence of a response alternative for this English vowel and most non-native vowels were predominantly assimilated to the fact that letter hui is a common spelling for both /ˆ/ and a single L1 category, receiving assimilation scores above a /U/ (e.g., putt and put) may have resulted in some /ˆ/ 70% categorization threshold (Tyler et al., 2014). The per- responses for Catalan /u/. Finally, Catalan /i, o, O/ obtained ceptual assimilation patterns did not always follow from scores below 70%. Catalan /i/ was split between English /i+/ the acoustic proximity observable on an F1 " F2 plot (see and /I/ (62% and 37%, respectively). Although Catalan /i/ is Fig. 2), particularly in the case of the back vowels. This is in acoustically closer to English /i+/ than to English /I/ line with previous works showing discrepancies between (Cebrian, 2006; see also Fig. 2), the Catalan /i/ stimuli were acoustic and perceptual measures (see Strange, 2007). An closer in duration to the latter than to the former (C /i/: examination of such discrepancies lies beyond the scope of 139 ms, E /I/: 136 ms, E / i+/: 168 ms). It is possible then this paper, whose focus is on perceptual data. Among the that the shorter duration of Catalan /i/ may have triggered single-category assimilations, a few patterned as good and some /I/-responses. This is in line with Escudero and fair matches (Guion et al., 2000). Both Catalan and English Boersma’s (2004) finding that native Southern British listeners predominantly linked Catalan and English diph- English speakers may attend to temporal and spectral cues thongs, indicating that diphthongs (often excluded from in their perception of the / i+/-/I/ contrast. In addition to /i/, vowel studies) play a relevant role in cross-linguistic per- the two Catalan mid back vowels (/O/ and /o/) obtained ception, in line with previous findings [e.g., Cebrian (2019) 2680 J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian https://doi.org/10.1121/10.0004257 and Escudero and Williams (2011) for Spanish and English by Catalan listeners, while the reverse was true for C-E /e/-/I/. diphthongs]. English /A+/ (as well as /U/ and /˘+/ according Speakers exposed to non-native or L2 sounds perceive them, to previous studies; see Footnote 3) and Catalan /i, o, O/ at least initially, as variations on L1 sounds (Schmidt, were the only cases of uncategorized vowels. The extent to 2007). Thus, differences between Catalan and English which English and Catalan listeners agreed in the judge- speakers in the GRs provided for the same C-E pairs may be ments of cross-linguistic similarity is discussed next. related to differences in the amount of within-category vari- ation and exposure to that variation in L1 speech. For A. Reciprocity in perceived similarity instance, SSBE speakers are exposed to /@U/ productions with a less central beginning (thus closer to C /ou/) as a One of the goals of this study was to examine to what & result of both allophonic variation (e.g., preceding consonants extent there is reciprocity in perceptual judgements of simi- like /l/) and dialectal variation. By contrast, Catalan listeners larity between native and non-native vowels as perceived by do not encounter centralized versions of stressed /ou/ in their native speakers of the two languages involved. The intention & match native input. Consequently, C /ou/ emerged as a better is to obtain a more complete picture of the similarity rela- & for E /@U/ than the reverse. tionships between Catalan and English vowels and to evalu- Two more pairs received parallel mappings in terms of ate whether some phones can be considered near-identical the modal responses, but with different categorization lev- or shared by both languages. In terms of modal responses, els. English /i+/ was categorized as C /i/ (87% assimilation there was a very high level of agreement between the two scores), but the reverse mapping was below 70% (62%). populations. Considering the number of Catalan stimuli was The difference was even greater with E /`/ and C /O/, which smaller (11 vowels and diphthongs tested, as opposed to 13 showed a consistent assimilation pattern with Catalan listen- in the case of the English stimuli), there were 11 potentially ers (82%) but only reached a 53% assimilation score reciprocal matches, that is, cases where the Catalan and with English listeners. Finally, C /o/ and E /O+/ did not English listeners could have provided the same native-non- receive reciprocal mappings. English listeners linked C /o/ native mappings. Figure 3 shows the pairs that obtained with E /`/ (59% assimilation scores), followed by E /O+/ reciprocity. Of the 11 possible matches, 8 received recipro- (18%), while Catalan listeners perceived E /O+/ predomi- cal modal responses with assimilation scores equal to nantly as C /o/ (77%). The discrepancy in the results for or higher than 70% (C-E /au/-/aU/, /E/-/E/, /a/-/æ/, /ou/-/@U/, Catalan /i, o, O/ may be linked to cross-linguistic differences /ei/-/eI/, /ai/-/aI/, /e/-/I/, and&/u/-/u+/). & in vowel duration, as discussed above, reflecting the way the & The very & consistent results for C-E /au/-/aU/, /E/-/E/, specific characteristics of the listener’s L1 affect cross- and /a/-/æ/ across experiments (good and fair &matches) point linguistic perception. Unlike English vowels, Catalan vow- to cases of near-identity and suggest that for both popula- els tend to vary little in duration, and their average duration tions, the non-native vowels would be readily perceived and is notably closer to the average duration of English lax vow- produced in terms of native categories. Contrasting the percep- els than of English tense vowels. Thus, the English listeners tual judgements of two parallel populations can shed light on a selected the lax vowel /I/ as the preferred match for the rela- basic question in phonetics, namely, when two sounds from tively short high front Catalan vowel more than a third of different languages can be considered the same (Ladefoged, the time. This resulted in a rather asymmetric pattern, with 1990). We can speculate that these vowels may not be distin- C-E /i/-/i+/ being judged as a good match by Catalan listen- guishable from native categories and that, when used in L2 ers and a poor match by English listeners. Similarly, despite speech, they may go unnoticed by target language speakers. In the quality difference between C /O/ and /o/ and the avail- addition, C-E mappings /ou/-/@U/, /ei/-/eI/, and /ai/-/aI/ were ability of different L1 back vowels, the Catalan vowels’ rel- considered fair matches by &English listeners & & matches but poor ative short duration rendered them unsuitable as instances of the comparatively long SSBE vowel /O+/ and triggered a two to one assimilation of C /O/ and /o/ to E /`/. The only previ- ous study that looked at reciprocal similarity, Schmidt (1996, 2007) on Japanese and English consonants, found a number of parallel or reciprocal mappings but also reported that cross-linguistic similarity varied for the two language groups depending on context-specific cues (e.g., the round- ing of adjacent vowels, differences in VOT, and the pres- ence of burst-like transitions in nasals). Schmidt (2007) suggests that adult L2 listeners attend to the phonetic cues that are relevant in the organization of sound contrasts in FIG. 3. Perceptual assimilation results from experiments 1 and 2. Double- their L1. Although native English speakers rely mainly on headed arrows indicate reciprocal modal responses. Single-headed arrows spectral cues to identify L1 vowels, temporal differences show unidirectional modal responses (or differences in amount of assimila- may also play a role (Escudero and Boersma, 2004; tion). Darker lines indicate good/fair matches, all solid lines indicate assim- ilation scores $70%, dashed lines indicate assimilation scores between Hillenbrand et al., 2000). In the current case, the lack of 50% and 70%. duration distinctions among the Catalan stimuli may have J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian 2681 https://doi.org/10.1121/10.0004257 rendered some non-native spectral differences like C /o/-/O/ Regarding English speakers, C /o/-/O/ constitutes an less interpretable in terms of available L1 categories. On the uncategorized-uncategorized pair with complete assimila- other hand, duration is not relevant for Catalan listeners who tion overlap as E /`/ and /O+/ (UU-C), while C /i/ and /e/ pat- predominantly mapped each non-native back vowel with a tern as a UC-P case, with partial overlap (as E /I/). different L1 vowel. The extent to which the two populations According to PAM, the UU-C contrasts will be the most dif- provide comparable similarity judgements is thus modulated ficult to discriminate for non-native speakers, followed by by the role of language-specific acoustic cues. Interestingly, the UC-P and CG cases, which will vary in accuracy having a larger inventory in the case of English does not depending on the degree of assimilation overlap. The result in more single-category assimilations. The relative remaining vowel combinations constitute two-category weighting of relevant L1 cues, such as duration, seems to assimilations (e.g., C /a/-/E/, E /æ/-/E/) or non-overlapping play a greater role than the possibility of finding a different categorized-uncategorized pairs (e.g., C /a/-/O/), which are anchor for each non-native vowel. expected to be more accurately discriminated [see Faris Of the two remaining English vowels, /ˆ/ was consis- et al. (2018) and Tyler (2021) for more discussion]. Testing tently perceived as C /a/, while English listeners selected /ˆ/ these predictions is beyond the scope of the current paper as a match for non-native Catalan vowels on few occasions and is left for further research. (12% for /o/ and /u/, 9% for /a/ and /O/). Similarly, Catalan listeners perceived E /A+/ as /O/ and /a/ (54% and 31% assimi- B. Limitations, final conclusions, and issues lation scores, respectively), but English listeners selected /A+/ for further study as a response for C /O/ and /a/ only 4% and 5% of the time. This study has some limitations. First, the study falls short Given that English has a larger number of vowels, it is logi- of a whole-system approach, where listeners identify all non- cal that some English vowels were not selected as modal native monophthongs and diphthongs in terms of the entire responses. This may indicate that these L1 vowels were con- vowel inventory of their L1 (Bundgaard-Nielsen et al., 2011; sidered by English listeners to be the most different from Faris et al., 2016). The current study excluded the English Catalan vowels. In that sense, the results for E /A+/ are consis- tent across language groups, as it is the vowel that received vowels /˘+/ and /U/ and did not include all the possible Catalan the lowest assimilation scores by Catalan listeners and the L1 diphthongs (combinations of the monophthongs and the semi- vowel that was used the least as a response by the English lis- vowels /i/ and /u/). The aim of this paper was to investigate & the reciprocity of& cross-linguistic perceptual assimilation, and teners. Regarding E /ˆ/ and /æ/, the former was hardly selected as a good match for C /a/ by English listeners (9%, thus the focus was on vowels that tended to be consistently cf. 86% for /æ/), while Catalan listeners linked E /ˆ/ predomi- categorized in previous studies involving Catalan listeners. nantly with C /a/ (98%) but with lower GRs and FI (FI of 5.5 Thus, English vowels /˘+/ and /U/ were excluded on the and 4.6 for /æ/ and /ˆ/, respectively). Hence, the results for grounds of previous results showing low degrees of assimila- both groups of listeners point to E /æ/ as being a better match tion for these vowels (see Footnote 3). Further, in an attempt for the C /a/ than E /ˆ/ and illustrate how the judgements from to create a more practical less fatigue-prone perceptual task, two parallel populations support the same findings. front and back vowels were tested in two separate blocks Finally, although not the focus of the current paper, a (tasks A and B), with a subset of the response options each. few predictions are briefly presented in relation to the mod- This division may have prevented the detection of some simi- els discussed in the Introduction. In terms of the SLM/SLM- larity relationships. For instance, the English central vowel /ˆ/, r (Flege, 1995; Flege and Bohn, 2021), differences between was included with the front vowels (task A), and thus listeners the L1 and the non-native vowels will be more likely to be could not choose one of the Catalan back vowels as responses detected in the case of poor matches, given enough exposure (task B). Still, the division into subtasks was guided by the to authentic target language input, than in the case of fair results of previous studies, and stimuli and responses were dis- matches. Those vowels that qualify as good matches may be tributed in such a way that all likely responses were available perceived as nearly identical to the native categories and be for each task. For instance, in a previous study in which all pos- readily accepted as instances of L1 vowels, and the resulting sible response options were presented in a single task (Cebrian single L1-L2 category may yield accurate perception and et al., 2011), E /ˆ/ was perceived as C /a/ much more often than production, particularly in cases of reciprocal assimilation as a back vowel like C /O/ (85% and 11%, respectively). (C-E /au/-/aU/, /E/-/E/, /a/-/æ/). With respect to PAM’s assim- Finally, it could be argued that the methodology could be & and the corresponding predictions, E /A+/ and C /i, ilation types improved with the addition of a “non-L1” response option so o, O/ were assimilated above chance to more than one L1 phone that listeners were not forced to choose one of the L1 categories and thus pattern as uncategorized-clustered (Faris et al., 2016). for uncategorizable non-native stimuli. However, the consis- For Catalan speakers, E /æ/-/ˆ/ constitute a category-goodness tency of the assimilation patterns and the use of goodness of fit (CG) assimilation,7 while E /A+/-/`/, /A+/-/æ/, and /A+/-/ˆ/ illus- data provide adequate evidence as to what non-native phones trate uncategorized-categorized assimilation types with partial cannot be categorized in terms of L1 categories. A “non-L1” assimilation overlap (UC-P; Faris et al., 2016) as C /O/, /a/, response option may be more informative for studies evaluating and /a/, respectively. These four pairs are predicted to pose whether cross-linguistic perceived similarity varies as a function the greatest discrimination difficulty for Catalan speakers. of L2 experience (Flege, 1991; Rallo Fabra and Romero, 2012). 2682 J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian https://doi.org/10.1121/10.0004257 Another limitation concerns the nature of the stimuli, Further research evaluating L2 learning is necessary to investi- which consisted of vowels produced in a single phonetic con- gate the extent to which these C-E pairs behave as near- text, between /b/ and /t/. It is known that perceived similarity identical or shared categories and are unnoticed when used in may vary depending on the phonetic and the prosodic context the non-native context, as well as examining cases of mis- (Strange et al., 2002). For instance, Bohn and Steinlen (2003) matched degree of assimilation and lower degrees of reciproc- found that Danish speakers with English language experience ity. An interesting issue in relation to cases of asymmetric classified English /i/ as instances of Danish /e/ in glottal and reciprocity (such as C-E /i/-/i+/) is what constitutes a better alveolar contexts but as /i/ in velar context. Levy (2009a) predictor of L2 learning difficulty, the perceived similarity reported that assimilation patterns of French vowels to English judgements of the L1 speakers or of the target language speak- vowels were more consistent in a bilabial context than in an ers. A few cases of lack of reciprocity were observed, which alveolar context. Clearly, a more complete description of underscore the role of language-specific cues such as duration, cross-linguistic similarity relations needs to include a wider as illustrated by the two to one assimilation of the Catalan mid variety of contexts. In addition, the current study has focused back vowels /o, O/ to the English vowel /`/. This study has not on two specific varieties of each language (Eastern Catalan examined the relationship between perceptual and acoustic and SSBE). It remains to be seen how cross-linguistic assimila- similarity or investigated other perceptual measures such as a tion patterns would differ for speakers of other varieties, e.g., paired comparison technique, i.e., dissimilarity ratings for for speakers of Majorcan Catalan, a variety that has a mid cen- pairs of native and non-native stimuli (Flege et al., 1994). tral vowel (/@/) as part of the stressed vowel inventory. These issues, together with the examination of a wider range To sum up, this study has examined the perceived simi- of phonetic and prosodic contexts and other varieties of larity between a near-complete set of SSBE and Catalan vow- Catalan and English, are left for further study. Still, we can els and diphthongs and has contrasted the perceptual conclude that reciprocal studies that include both L1 identifi- judgements of Catalan and English listeners. The cross- cation and non-native assimilation data can achieve a more language assimilation scores have been compared to L1 iden- complete assessment of cross-linguistic similarity and can tification results to evaluate the degree to which non-native help develop hypotheses about non-native perception and L2 vowels assimilate to L1 vowels. The results show that most learning, in addition to bringing us closer to a better under- non-native vowels received very consistent degrees of assimi- standing of the concept of phonetic similarity. lation in terms of L1 vowels, with varying degrees of good- ness of fit. The inclusion of L1 stimuli in the perceptual task ACKNOWLEDGMENTS has made it possible to assess that some high assimilation rates The author is grateful to Joan Carles Mora for his help were comparable to the identification scores received by with the elicitation of the Catalan production data for the native vowels. In addition, by testing speakers of the two lan- Catalan vowel stimuli. This work was supported by Research guages being compared, it has been found that the majority of Grant No. FFI2017-88016-P from the Spanish Ministry of the vowels were involved in reciprocal mappings, including Economy and Competitiveness and by Research Group some of the most strongly assimilated pairs (e.g., C-E /au/-/aU/, & Grant No. 2017SGR34 from the Catalan Government. /E/-/E/, /a/-/æ/). The interpretation of cross-linguistic assimi- lation patterns in relation to L1 identification data and the APPENDIX comparison of perceptual judgements from speakers of the two languages involved are thus proposed as a suitable Confusion matrices displaying the percentage of novel approach to assess phonetic similarity and to answer responses for each stimulus vowel in experiment 1 and questions about cross-linguistic identity (Ladefoged, 1990). experiment 2 are shown in Tables V and VI. TABLE V. Experiment 1: Percentage assimilation of SSBE vowels to Catalan vowels (Cat. resp.). GRs are given in parentheses. Modal responses appear in boldface. Assimilations below 3% have been excluded. Note: See Footnote 3 for results for English /˘+/ and /U/ reported in previous studies. English vowel stimuli Cat. resp. /i:/ /I/ /eI/ /E/ /æ/ /ˆ/ /aI/ /aU/ /@U/ /A:/ /`/ /O:/ /u:/ /i/ 87 (5.7) 12 (3.8) 3 (1.9) /e/ 80 (5.6) 8 (5.1) /ei/ 12 (4.2) 76 (4.2) & /E/ 7 (4.8) 91 (5.6) /a/ 99 (5.6) 98 (4.7) 31 (3.9) 3 (3.7) /ai/ 21 (4.3) 95 (3.6) & /au/ 99 (4.9) 19 (2.6) 11 (2.3) 3 (1.9) 8 (1.2) & /ou/ 79 (3.7) 8 (3.4) 10 (2.4) & /O/ 54 (4.8) 82 (5) 7 (3.5) /o/ 4 (4.5) 11 (4.6) 77 (4.8) /u/ 6 (3.9) 82 (3.7) J. Acoust. Soc. Am. 149 (4), April 2021 Juli Cebrian 2683 https://doi.org/10.1121/10.0004257 TABLE VI. Experiment 2: Percentage assimilation of Catalan vowels to SSBE vowels (Eng. resp.). Goodness ratings are given in parentheses. Modal responses appear in boldface. Assimilations below 3% have been excluded. Catalan vowel stimuli Eng. resp. /i/ /e/ /ei/ /E/ /a/ /ai/ /au/ /ou/ /O/ /o/ /u/ & & & & /i:/ 62 (4.5) 6 (4.3) /I/ 37 (4.3) 73 (5) /eI/ 94 (5) 8 (4.5) /E/ 24 (3.7) 92 (4.9) /æ/ 6 (2.9) 86 (5.3) /ˆ/ 9 (4.5) 9 (4.2) 12 (4) 12 (3.4) /aI/ 91 (5.2) /aU/ 94 (5.4) /A:/ 5 (3.6) /@U/ 97 (5) 11 (3.1) 12 (3.1) /`/ 53 (5) 59 (4.4) /O:/ 5 (3.2) 33 (4.3) 18 (3.8) /u:/ 70 (4.1) 1 See also Daidone et al. (2015) for another technique referred to as the free Baigorri, M., Campanelli, L., and Levy, E. S. (2019). “Perception of classification task in which participants group stimuli in terms of percep- American-English vowels by early and late Spanish-English bilinguals,” tual closeness by moving visual representations of the stimuli on a com- Lang. Speech 62(4), 681–700. puter screen. Best, C. (1995). “A direct realist view of cross-language speech 2 Note that in Catalan, the symbol /O/ is used to represent the lowest of the perception,” in Speech Perception and Linguistic Experience: Theoretical mid back rounded vowels (/o, O/), while in SSBE, /O+/ represents a vowel and Methodological Issues, edited by W. Strange (York, Timonium, that is higher than the low back rounded vowel /`/. MD), pp. 171-204. 3 Best, C. T., and Tyler, M. D. (2007). “Nonnative and second-language speech For example, Cebrian et al. (2011) found that English /˘+/ was assimilated to Catalan /e/ 30% of the time, followed by /E/ (24%), /a/ (23%), /o/ (9%), perception: Commonalities and complementarities,” in Language Experience and /O/ (9%). Rallo Fabra (2005) reported that English /U/ was identified in Second Language Speech Learning: In Honor of James Flege, edited by as Catalan /u/ (31%), /o/ (16%), /e/ (12%), and /O/ (7%) and was perceived M. Munro, and O.-S. Bohn (John Benjamins, Amsterdam), pp. 13–34. as “not Catalan” 30% of the time. Boersma, P., and Weenink, D. (2018). “Praat: Doing phonetics by computer 4 An anonymous reviewer pointed out possible dialectal variation regarding (version 6.0.43) [Computer program],” http://www.praat.org/ (Last viewed the pronunciation of the word mot (with /o/ or /O/). While this has been September 8, 2018). attested for Valencian Catalan, most sources indicate /o/ as the only or Bohn, O.-S. (2002). “On phonetic similarity,” in An Integrated View of predominant pronunciation in Central or Eastern Catalan (e.g., Alcover Language Development: Papers in Honor of Henning Wode, edited by P. and Moll, 1993). In addition, the participants in the current study were Burmeister, T. Piske, and A. Rohde (Wissenschaftlicher Verlag, Trier), asked at the beginning of the PAT to consider the response options and pp. 191–216. indicate if any differed from their own pronunciation. 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