Phonetics

Sound, structure and meaning: The bases of prominence ratings in English, French and Spanish Publication date: July 2019 Source: Journal of Phonetics, Volume 75 Author(s): Jennifer Cole, José I. Hualde, Caroline L. Smith, Christopher Eager, Timothy Mahrt, Ricardo Napoleão de Souza Abstract This study tests the influence of acoustic cues and non-acoustic contextual factors on listeners’ perception of prominence in three languages whose prominence systems differ in the phonological patterning of prominence and in the association of prominence with information structure—English, French and Spanish. Native speakers of each language performed an auditory rating task to mark prominent words in samples of conversational speech under two instructions: with prominence defined in terms of acoustic or meaning-related criteria. Logistic regression models tested the role of task instruction, acoustic cues and non-acoustic contextual factors in predicting binary prominence ratings of individual listeners. In all three languages we find similar effects of prosodic phrase structure and acoustic cues (F0, intensity, phone-rate) on prominence ratings, and differences in the effect of word frequency and instruction. In English, where phrasal prominence is used to convey meaning related to information structure, acoustic and meaning criteria converge on very similar prominence ratings. In French and Spanish, where prominence plays a lesser role in signaling information structure, phrasal prominence is perceived more narrowly on structural and acoustic grounds. Prominence ratings from untrained listeners correspond with ToBI pitch accent labels for each language. Distinctions in ToBI pitch accent status (nuclear, prenuclear, unaccented) are reflected in empirical and model-predicted prominence ratings. In addition, words with a ToBI pitch accent type that is typically associated with contrastive focus are more likely to be rated as prominent in Spanish and English, but no such effect is found for French. These findings are discussed in relation to probabilistic models of prominence production and perception.

Plasticity of native phonetic and phonological domains in the context of bilingualism Publication date: July 2019 Source: Journal of Phonetics, Volume 75 Author(s): Esther de Leeuw, Chiara Celata Abstract The main point of this introduction, and therefore of the special issue, is to reveal and emphasise research findings which show that the domains of phonetics and phonology are malleable in adult native speech within the context of bilingualism. The manuscripts reveal this general finding through examination of a wide range of bilinguals using various methodologies. We believe that this finding is important for our understanding of the human capacity for language. Firstly, it is important because most humans speak more than one language. Therefore, to understand the human capacity for language, it is imperative to examine that majority. Moreover, this finding, that native phonetic and phonological domains are malleable throughout the lifespan in the context of bilingualism, is not an entirely accepted claim throughout research in linguistics. The idea that the native language stabilises at the latest in adolescence is still pervasive. Therefore, the findings presented in this special issue challenge a long held assumption. At a theoretical level, such studies revealing plasticity of native phonetic and phonological domains in the context of bilingualism substantiate a shift in research into cognition, indicating that the brain is malleable throughout life in both language and non-language domains.

Contextual predictability and phonetic attention Publication date: July 2019 Source: Journal of Phonetics, Volume 75 Author(s): Jonathan Manker Abstract The interaction of contextual, high-level linguistic knowledge and the listener’s attention to low-level phonetic details has been the subject of a large body of research in speech perception for several decades. In the current paper, I investigate this interaction by considering the specific phenomenon of word predictability and its role in modulating the listener’s attention to subphonemic details of the acoustic signal. In the first experiment, subjects are presented with a discrimination task in which target words are presented in either predictable or unpredictable sentential context and then repeated in isolation, being either acoustically identical or subtly different. The subjects more accurately discriminate contextually unpredictable words, suggesting more attention to the phonetic details of words in unpredictable contexts. In the second experiment, considering the predictions of exemplar theory, I test whether this perceptual bias could result in changes in production. In this experiment, in which subjects heard and repeated sentences, I find a significant effect of word predictability on how close the subjects’ productions were to the model’s, which suggests a role of predictability on phonetic accommodation. The results of these experiments contribute to our understanding of stored exemplars and suggest the influence of contextual predictability in sound change.

Statistical distributions of consonant variants in infant-directed speech: Evidence that /t/ may be exceptional Publication date: July 2019 Source: Journal of Phonetics, Volume 75 Author(s): Laura Dilley, Jessica Gamache, Yuanyuan Wang, Derek M. Houston, Tonya R. Bergeson Abstract Statistical distributions of phonetic variants in spoken language influence speech perception for both language learners and mature users. We theorized that patterns of phonetic variant processing of consonants demonstrated by adults might stem in part from patterns of early exposure to statistics of phonetic variants in infant-directed (ID) speech. In particular, we hypothesized that ID speech might involve greater proportions of canonical /t/ pronunciations compared to adult-directed (AD) speech in at least some phonological contexts. This possibility was tested using a corpus of spontaneous speech of mothers speaking to other adults, or to their typically-developing infant. Tokens of word-final alveolar stops – including /t/, /d/, and the nasal stop /n/ – were examined in assimilable contexts (i.e., those followed by a word-initial labial and/or velar); these were classified as canonical, assimilated, deleted, or glottalized. Results confirmed that there were significantly more canonical pronunciations in assimilable contexts in ID compared with AD speech, an effect which was driven by the phoneme /t/. These findings suggest that at least in phonological contexts involving possible assimilation, children are exposed to more canonical /t/ variant pronunciations than adults are. This raises the possibility that perceptual processing of canonical /t/ may be partly attributable to exposure to canonical /t/ variants in ID speech. Results support the need for further research into how statistics of variant pronunciations in early language input may shape speech processing across the lifespan.

Spontaneous nasalization after glottal consonants in Thai Publication date: July 2019 Source: Journal of Phonetics, Volume 75 Author(s): Sarah E. Johnson, Marissa Barlaz, Ryan K. Shosted, Brad P. Sutton Abstract Spontaneous nasalization is the emergence of distinctive nasalization in contexts lacking an historical etymological nasal. In Thai, low and mid-low vowels nasalize after /h/ and to a lesser degree after /ʔ/. It has been reasoned that nasalization after /h/ may occur because breathiness and nasalization are acoustically similar; both introduce higher energy at low frequencies and increase spectral tilt. Glottal consonants may generally facilitate nasalization because aerodynamically they do not require velopharyngeal closure. We investigated velopharyngeal opening (VPO) during vowels after /h/ and/ ʔ/ and measured spectral tilt (H1–H2). We measured VPO by processing oblique ultra-fast magnetic resonance images of the velopharyngeal port. Four Thai speakers exhibited a complex system of VPO that varied based on vowel height and preceding consonant. Low vowels after /h/ manifested more physiological nasalization than low vowels after /ʔ/, while the former were often produced with higher spectral tilt, which may be indicative of either increased breathiness or nasalization. While VPO is likely responsible for impressions of greater nasalization after /h/, our findings suggest that breathiness and VPO may interact in the spontaneously nasalized vowels of Thai.

Influence of coda stop features on perceived vowel duration Publication date: July 2019 Source: Journal of Phonetics, Volume 75 Author(s): Chelsea Sanker Abstract Four experiments tested what cues contribute to English speakers’ perception of vowel duration. Listeners categorized the duration of vowels as ‘long’ or ‘short’ for stimuli produced with voiced, voiceless, breathy voiced, or voiceless aspirated stop codas. Listeners demonstrated a strong ability to perceive vowel duration, though perception was continuous rather than categorical. There were several interacting factors influencing perceived vowel duration, based on expectations set by the presence of particular codas and also acoustic effects of the coda on the vowel. When the coda was removed, vowels that had been produced before voiced codas were perceived as longer than vowels produced before voiceless codas, though they exhibited the opposite effect when codas were present. Vowels were also perceived as longer when produced before breathy voiced stops, regardless of whether or not the stop was present. The steeper f0 falls associated with voiced codas within these stimuli likely contributed to the longer perceived duration of vowels from this environment; manipulating f0 contours eliminated effects of the original coda on perceived vowel duration. The effects of the production environment on perceived vowel duration suggest a possible perceptual pathway for the voicing effect on vowel duration.

Cue-shifting between acoustic cues: Evidence for directional asymmetry Publication date: July 2019 Source: Journal of Phonetics, Volume 75 Author(s): Meng Yang, Megha Sundara Abstract Previous research shows that experience with co-varying cues is neither sufficient nor necessary for listeners to integrate them perceptually. Auditory Enhancement theorists explain this by positing that listeners integrate two cues more readily if the cues enhance each other’s percept. To isolate the role of enhancement from that of experience, we forced English adult listeners to shift attention between two enhancing cues that they do not use phonemically, pitch and breathiness, by reversing the informativeness of the two cues in a cue weighting experiment. Listeners were able to shift attention from pitch to breathiness and vice versa if the two cues were in an enhancing relation. When this relationship was reversed, listeners could shift attention from pitch to breathiness but not in the opposite direction. Clearly, both the change in informativeness and the enhancing properties of the cues influenced the listeners’ re-weighting of these cues. However, the directional asymmetry was not predicted. Moreover, the same asymmetry was observed in two new groups of listeners who have native language experience with either pitch or breathiness. We discuss the consequences of such asymmetric enhancement effects, rising from either processing limitations or articulatory contingencies, for language change.

Formant dynamics of Spanish vocalic sequences in related speakers: A forensic-voice-comparison investigation Publication date: July 2019 Source: Journal of Phonetics, Volume 75 Author(s): Eugenia San Segundo, Junjie Yang Abstract This study investigates the dynamic acoustic properties of 19 vocalic sequences of Standard Peninsular Spanish, showing their potential for forensic voice comparison. Parametric curves (polynomials and discrete cosine transform) were fitted to the formant trajectories of the 19 Spanish vocalic sequences of 54 male speakers, comprising monozygotic (MZ) and dizygotic (DZ) twin pairs, non-twin brothers and unrelated speakers. Using the curve-fitting estimated coefficients as input to a multivariate-kernel-density formula, cross-validated likelihood ratios were calculated to express the probability of obtaining the observed difference between two speech samples under the hypothesis that the samples were produced by the same speaker and under the hypothesis that they were produced by a different speaker. The results show that the best-performing system is one that fuses the 19 vocalic sequences with a geometric-mean fusion method. When challenging the system with related speakers, the results show that MZ twin pairs affect performance but, more importantly, that non-twin sibling pairs can deteriorate performance too. This suggests that more investigations are necessary into a range of similar-sounding speakers beyond MZ twins. Several nurture aspects are highlighted as explanatory factors for the strikingly high similarity of a specific non-twin sibling pair.

Alignment of f0 peak in different pitch accent types affects perception of metrical stress Publication date: May 2019 Source: Journal of Phonetics, Volume 74 Author(s): Katharina Zahner, Sophie Kutscheid, Bettina Braun Abstract In intonation languages, pitch accents are associated with stressed syllables, therefore accentuation is a sufficient cue to the position of metrical stress in perception. This paper investigates how stress perception in German is affected by different pitch accent types (with different f0 alignments). Experiment 1 showed more errors in stress identification when f0 peaks and stressed syllables were not aligned – despite phonological association of pitch accent and stressed syllable. Erroneous responses revealed a response bias towards the syllable with the f0 peak. In a visual-world eye-tracking study (Experiment 2), listeners fixated a stress competitor with initial stress more when the spoken target, which had penultimate stress, was realized with an early-peak accent (f0 peak preceding stressed syllable), compared to a condition with the f0 peak on the stressed syllable. Hence, high-pitched unstressed syllables are temporarily interpreted as stressed – a process directly affecting lexical activation. To investigate whether this stress competitor activation is guided by the frequent co-occurrence of high f0 and lexical stress, Experiment 3 increased the frequency of low-pitched stressed syllables in the immediate input. The effect of intonation on competitor fixations disappeared. Our findings are discussed with respect to a frequency-based mechanism and their implications for the nature of f0 processing.

Language change and linguistic inquiry in a world of multicompetence: Sustained phonetic drift and its implications for behavioral linguistic research Publication date: May 2019 Source: Journal of Phonetics, Volume 74 Author(s): Charles B. Chang Abstract Linguistic studies focusing on monolinguals have often examined individuals with considerable experience using another language. Results of a methodological review suggest that conflating ostensibly ‘multicompetent’ individuals with monolinguals is still common practice. A year-long longitudinal study of speech production demonstrates why this practice is problematic. Adult native English speakers recently arrived in Korea showed significant changes in their production of English stops and vowels (in terms of voice onset time, fundamental frequency, and formant frequencies) during Korean classes and continued to show altered English production a year later, months after their last Korean class. Consistent with an Incidental Processing Hypothesis (IPH) concerning the processing of ambient linguistic input, some changes persisted even in speakers who reported limited active use of Korean in their daily life. These patterns thus suggest that the linguistic experience obtained in a foreign language environment induces and then prolongs restructuring of the native language, making the multicompetent native speaker in a foreign language environment unrepresentative of a monolingual in a native language environment. Such restructuring supports the view that one’s native language continues to evolve in adulthood, highlighting the need for researchers to be explicit about a population under study and to accordingly control (and describe) language background in a study sample.