Jessamyn Schertz

Exaggeration of featural contrasts in clarifications of misheard speech in English

Abstract This study investigates the extent to which speakers manipulate featural distinctions when trying to clarify misunderstood speech, focusing on voicing contrasts in stops and height and backness (represented by F 1 and F 2) and durational contrasts in vowels. Participants interacted with a simulated speech recognizer, repeating words when they were “guessed” incorrectly. Both phonemically voiced and voiceless stops showed more extreme VOT values when elicited by an incorrect guess in which the consonant was a minimal pair in voicing with the target consonant (e.g. subject reads “bit”, computer guesses “pit”), but not when elicited by an open-ended request for repetition (e.g. subject reads “bit”, computer guesses “What did you say?”). A follow-up study showed that the change in VOT between the two repetitions was only present when the incorrect guess contrasted in voicing, but not when it contrasted in place or manner. In contrast, for vowels, the amount and direction of formant change in the F 1– F 2 space was not significantly different from zero for either type of incorrect guess. However, when there was a durational component to the vowel contrast (/i/ vs. / ɪ / ), speakers exaggerated the durational differences between the segments, as opposed to when there was not a durational contrast (e.g. /i/ vs. /u/). The results show that speakers perform local, systematic, and phonologically informed manipulations of temporal contrasts online when clarifying phonetic segments.

Individual differences in perceptual adaptability of foreign sound categories.

Listeners possess a remarkable ability to adapt to acoustic variability in the realization of speech sound categories (e.g., different accents). The current work tests whether non-native listeners adapt their use of acoustic cues in phonetic categorization when they are confronted with changes in the distribution of cues in the input, as native listeners do, and examines to what extent these adaptation patterns are influenced by individual cue-weighting strategies. In line with previous work, native English listeners, who use voice onset time (VOT) as a primary cue to the stop voicing contrast (e.g., ‘pa’ vs. ‘ba’), adjusted their use of f0 (a secondary cue to the contrast) when confronted with a noncanonical “accent” in which the two cues gave conflicting information about category membership. Native Korean listeners’ adaptation strategies, while variable, were predictable based on their initial cue weighting strategies. In particular, listeners who used f0 as the primary cue to category membership adjusted their use of VOT (their secondary cue) in response to the noncanonical accent, mirroring the native pattern of “downweighting” a secondary cue. Results suggest that non-native listeners show native-like sensitivity to distributional information in the input and use this information to adjust categorization, just as native listeners do, with the specific trajectory of category adaptation governed by initial cue-weighting strategies.

The aerodynamic puzzle of nasalized fricatives: Aerodynamic and perceptual evidence from Scottish Gaelic

Abstract Scottish Gaelic is sometimes described as having nasalized fricatives (/ṽ/ distinctively, and [f̃, x̃, h̃], etc. through assimilation). However, there are claims that it is not aerodynamically possible to open the velum for nasalization while maintaining frication noise. We present aerodynamic data from 14 native Scottish Gaelic speakers to determine how the posited nasalized fricatives in this language are realized. Most tokens demonstrate loss of nasalization, but nasalization does occur in some contexts without aerodynamic conflict, e.g., nasalization with the consonant realized as an approximant, nasalization of [h̃], nasalization on the preceding vowel, or sequential frication and nasalization. Furthermore, a very few tokens do contain simultaneous nasalization and frication with a trade-off in airflow. We also present perceptual evidence showing that Gaelic listeners can hear this distinction slightly better than chance. Thus, instrumental data from one of the few languages in the world described as having nasalized fricatives confirms that the claimed sounds are not made by producing strong nasalization concurrently with clear frication noise. Furthermore, although speakers most often neutralize the nasalization, when they maintain it, they do so through a variety of phonetic mechanisms, even within a single language.

Variability in the pronunciation of non-native English the: Effects of frequency and disfluencies

Abstract This study examines how lexical frequency and planning problems can predict phonetic variability in the function word ‘the’ in conversational speech produced by non-native speakers of English. We examined 3180 tokens of ‘the’ drawn from English conversations between native speakers of Czech or Norwegian. Using regression models, we investigated the effect of following word frequency and disfluencies on three phonetic parameters: vowel duration, vowel quality, and consonant quality. Overall, the non-native speakers showed variation that is very similar to the variation displayed by native speakers of English. Like native speakers, Czech speakers showed an effect of frequency on vowel durations, which were shorter in more frequent word sequences. Both groups of speakers showed an effect of frequency on consonant quality: the substitution of another consonant for /ð/ occurred more often in the context of more frequent words. The speakers in this study also showed a native-like allophonic distinction in vowel quality, in which /ði/ occurs more often before vowels and /ðə/ before consonants. Vowel durations were longer in the presence of following disfluencies, again mirroring patterns in native speakers, and the consonant quality was more likely to be the target /ð/ before disfluencies, as opposed to a different consonant. The fact that non-native speakers show native-like sensitivity to lexical frequency and disfluencies suggests that these effects are consequences of a general, non-language-specific production mechanism governing language planning. On the other hand, the non-native speakers in this study did not show native-like patterns of vowel quality in the presence of disfluencies, suggesting that the pattern attested in native speakers of English may result from language-specific processes separate from the general production mechanisms.

Featural enhancement of Spanish word-initial stops in clarifications of misheard words

In an experiment exploring phonetic featural enhancement in Spanish, native speakers were asked to read words aloud, then repeat them when a supposed automatic speech recognizer “guessed” incorrectly (e.g. subject says “basta,” computer displays (in Spanish) “Did you say ‘pasta’?”, subject repeats “basta”). In a previous experiment with the same paradigm, English speakers exaggerated VOT in the second repetition (longer prevoicing for voiced and longer aspiration for voiceless stops) when the incorrect guess was a minimal pair in voicing with the target word. Spanish speakers also had longer prevoicing durations for voiced stops, but unlike English speakers, showed no change in VOT for voiceless stops; in fact, VOT was shorter in the clarification, though not significantly. The differences in how speakers of the two languages manipulated the stops reflects cross‐linguistic differences in the phonetic components of the stop contrast. Additionally, Spanish speakers produced fricatives for some of the word‐i...

Effect of L1 phonation contrast on production of L2 English stops

This work examines the influence of native phonation contrast type on the production of English stops in different phonetic contexts/reading styles. Proficient English speakers from four different L1 language backgrounds produced words in three different contexts: words in isolation, phrase-final in a carrier sentence, and in a reading passage. Language backgrounds were representative of three types of phonation contrasts: Mandarin (aspiration contrast: [pʰ ~ p]), Tagalog (voicing contrast: [p ~ b]), and Urdu (4-way phonation contrast [pʰ ~ p ~ bʰ ~ b]). 11 participants from each group were compared with a control group of L1 English speakers. Aspiration and closure voicing were measured. All groups produced English voiceless stops as aspirated; however, there was considerable variation in the voiced stops, with Mandarin speakers producing less voicing, and Urdu and Tagalog speakers producing more voicing, than English speakers across speech styles, showing an asymmetrical influence of L1 phonation on production of the English contrast, in line with other recent work.This work examines the influence of native phonation contrast type on the production of English stops in different phonetic contexts/reading styles. Proficient English speakers from four different L1 language backgrounds produced words in three different contexts: words in isolation, phrase-final in a carrier sentence, and in a reading passage. Language backgrounds were representative of three types of phonation contrasts: Mandarin (aspiration contrast: [pʰ ~ p]), Tagalog (voicing contrast: [p ~ b]), and Urdu (4-way phonation contrast [pʰ ~ p ~ bʰ ~ b]). 11 participants from each group were compared with a control group of L1 English speakers. Aspiration and closure voicing were measured. All groups produced English voiceless stops as aspirated; however, there was considerable variation in the voiced stops, with Mandarin speakers producing less voicing, and Urdu and Tagalog speakers producing more voicing, than English speakers across speech styles, showing an asymmetrical influence of L1 phonation on pro...

A bear called Baddington? Variability and contrast enhancement in accented infant-directed speech

This work examines the realization of the English stop voicing contrast in read speech directed to infants (IDS) and adults (ADS), as well as in words in isolation, as produced by three groups of speakers: native speakers of Canadian English (where /b/ and /p/ differ in aspiration), native speakers of languages in which /b/ and /p/ differ in phonetic voicing (e.g., Spanish), and native speakers of languages which have a 4-way stop contrast /b, p, bʰ, pʰ/, where both aspiration and voicing are contrastive (e.g., Hindi). In words in isolation, speakers from both “accented” groups tended to produce English voiceless stops as unaspirated, and voiced stops as phonetically voiced. However, there was variability in accented speakers’ voiceless stops, as well as in native speakers’ use of phonetic voicing in voiced stops, and this variability appeared to be augmented in the read speech conditions (ADS and IDS). We test the hypotheses (1) that IDS results in phonologically-informed contrast enhancement, with accen...

Top-down influence on phonetic categorization of native vs. non-native speech

Speech perception requires integration of multiple sources of information, including bottom-up acoustic information and top-down contextual information, and listeners may adjust their reliance on a given source of information depending on the communicative context. This work tests the hypothesis that listeners increase reliance on contextual, relative to acoustic, information when listening to a talker with a foreign accent, under the assumption that the bottom-up information (non-native pronunciation) may be less reliable. Native English listeners categorized an utterance-final target word, where the initial consonant systematically varied in voice onset time (VOT), as either “goat” or “coat.” Target words were embedded in carrier sentences contextually biased towards one of the words (e.g., “The girl milked the [coat/goat]” vs. “The girl put on her [coat/goat]”). Stimuli were created from productions by two talkers: a native English talker and a native Mandarin/L2 English talker with a discernable forei...

Cross-language correspondences in the face of change: Phonetic independence versus convergence in two Korean-Mandarin bilingual communities:

Aims and Objectives/Purpose/Research Questions: We investigate the robustness of cross-language phonetic correspondences in two bilingual communities over time, focusing on whether corresponding sounds (e.g. Mandarin /s/ and Korean /s’/) remain coupled in the face of language change, or whether the categories diverge over time in younger, more proficient bilinguals. Design/Methodology/Approach: We quantify the extent of assimilation versus independence of categories across languages by comparing bilinguals’ production of place of articulation and laryngeal contrasts in Mandarin and Korean sibilants. Distinct language-internal changes were expected on each dimension. Data and analysis: 107 speakers varying in age (aged 19–83), gender, and dialect participated in the study. Acoustic measurements (center of gravity of frication, voice onset time) and statistical analyses were performed on a total of ~11,000 tokens. Findings/Conclusions: The extent of cross-language independence differed on the two dimensions. Corresponding segments across the two languages remained tightly coupled in terms of place of articulation, even in the face of change; on the other hand, a language-internal change in the Korean laryngeal contrast left corresponding Mandarin segments unaffected, resulting in divergence of originally corresponding categories. We also found unpredicted changes on each dimension, and these changes progressed concurrently in the two languages. Originality: The study of correspondences in the context of independent sound change provides a unique perspective from which to evaluate the robustness of cross-language interaction, and the parallel analysis of two separate dimensions in two communities adds to the generalizability of results. Significance/Implications: Most changes occurred concurrently in the two languages, suggesting that similar phonetic categories across languages can remain tightly coupled, even in highly proficient bilinguals where phonetic independence is expected. However, one of the primary expected changes (voice onset time merger in Korean) did not affect corresponding segments in Mandarin, indicating that the extent of cross-language independence in phonetic correspondences may differ even within the same population. We discuss potential reasons for the different results.

Vowels of Korean dialects

This study compares the monophthongal vowels /a ɛ e i ʌ ɨ o u/ of two North Korean dialects as spoken by ethnic Koreans in China (24 Phyeongan and 21 Hamkyoung) with the vowels of Seoul Korean (25 younger and 32 older). Younger and older speakers of Seoul Korean are compared to examine the sound change in progress in Seoul. The most striking difference among the dialects is in the realization of /o/ and /ʌ/. In Seoul, /o/ is produced higher than /ʌ/. In Phyeongan, /o/ is lower than /ʌ/, while in Hamkyoung, the two are comparable in height and the main contrast is along F2. Also, /e/-/ɛ/ contrast is lost in Seoul but robust in the Northern dialects. Within Seoul Korean, the back vowel shift observed in recent literature is confirmed (Cho S. 2003, Han J. and Kang H. 2013, and Kang Y. to appear)—/o/ is raised toward /u/ while /ɨ/ is fronted away from /u/ in younger speakers’ speech. In contrast to recent reports of /u/-/ɨ/ and /o/-/ʌ/ merger in homeland North Korean dialects (Kang S. 1996, 1997, Kwak 2003, a...