Study on interactions between voicing production and perception using auditory feedback paradigm

There is ample evidence that motor learning changes the function of perceptual systems. Previous studies examining the interactions between speech production and perception have shown that the discrimination of phonetic contrasts characterized by the difference in articulatory place features is altered following their production changes caused by the perturbation of auditory feedback. The present study focused on a voiced-voiceless contrast in stop consonants, which is characterized by a temporal articulatory parameter, voice-onset time (VOT). In the experiment, we manipulated the participants' motor functions concerning VOT using a cross-categorical auditory feedback (CAF) paradigm (Mitsuya et al. in J Acoust Soc Am 135:2986-2994, 2014), in which a pre-recorded syllable sound starting with a voiced stop consonant (/da/) was fed back simultaneously with the participant's utterance of a voiceless stop consonant (/ta/), and vice versa. The VOT difference between /da/ and /ta/ productions was increased by the CAF, which is consistent with the result of Mitsuya's study. In addition, we conducted perceptual identification tasks of /da/-/ta/ continuum stimuli varying in VOT before and after the CAF task, and found that the identification function became sharper after as compared to before the CAF task. A significant positive correlation between such production and perception changes was also found. On the basis of these results, we consider that the change in motor function concerning VOT affected voiced-voiceless perceptual processing. The present study is the first to show the involvement of the speech production system in the perception of phonetic contrasts characterized by articulatory temporal features.

Aims and objectives: This study examines how cognate status and elicitation tasks affect Voice Onset Time (VOT) production in advanced Japanese-English bilinguals. It investigates whether bilinguals exhibit phonetic cross-linguistic influence in both their first (L1) and second (L2) languages and compares their L2 productions to a native English baseline to assess phonetic attainment. Design/methodology/approach: VOT data for word-initial /k/ were collected from 28 advanced Japanese-English bilinguals and a control group of 6 native English speakers. Participants produced cognate and non-cognate words in both Japanese (bilinguals only) and English using two tasks: picture naming and sentence reading. Data and analysis: A total of 2016 tokens from the bilinguals and 216 from the native speakers were acoustically analyzed. Mean VOT values were submitted to a mixed-design ANOVA to compare the groups’ English productions and a repeated-measures ANOVA to analyze the bilinguals’ productions across both languages. Findings/conclusions: A significant three-way interaction between Language, Word Status, and Task Type was found for the bilinguals, indicating that the phonetic cognate effect is modulated by both the language context and task demands. Critically, bilinguals exhibited a significant cognate effect in their English productions (shorter VOTs for cognates), a pattern not found to be statistically significant in the native speaker group. Bilinguals’ English VOTs were also significantly shorter overall than those of the native speakers. Originality: This study is the first to investigate phonetic cognate effects in a language pair with differing orthographies (Japanese-English) while also comparing different production tasks and including a native-speaker baseline. Significance/implications: The results provide robust evidence for the continuous co-activation of a bilingual’s two languages during speech production. The findings are discussed within an exemplar-based model of bilingual phonology, highlighting the intricate interplay of lexical and phonetic factors in shaping bilingual speech.

Why are Korean tense stops acquired so early?: The role of acoustic properties

Effective human speech requires the neural integration of ongoing vocal production with the auditory and somatosensory feedback signals that are produced. We are using invasive electrophysiology techniques in patient volunteers undergoing neurosurgical treatment in order to gain insights into these mechanisms and underlying neural circuits. By using multi-contact electrode arrays chronically implanted over the perisylvian temporal lobe auditory cortex (e.g. area PLST) and the inferior frontal gyrus (IFG), we can examine local field potentials and frequency-specific responses from cortical areas important for both vocal production and speech sound processing. Our initial studies have found that during self-vocalization, focal areas within higher order auditory cortex on the superior temporal gyrus (STG) show response modulation compared to the responses of the same areas during passive listening. Manipulation of the auditory feedback that a speaker receives during vocalization (e.g. pitch-shifted or delayed auditory feedback) leads to further modulation of these PLST sites. Measures of functional connectivity including electrical stimulation tract tracing or phase-synchrony analysis demonstrate that portions of PLST are functionally connected to regions of the IFG. These findings support forward models for vocal control in which efference copies of premotor cortex activity modulate sub-regions of auditory cortex.

This study investigates learners’ implicit knowledge of Voice Onset Time (VOT), a non-distinctive phonetic difference between German and French. Previous studies on VOT in speech produced by English native speakers learning Spanish (Flege & Hammond 1982) and L1 Spanish-speaking learners of English (Mora et al. 2014) suggest that learners modify their native VOT patterns when attempting to imitate a foreign accent. This was taken as evidence for the development of tacit awareness of cross-language VOT difference between L1 and L2 voiceless stops. In order to determine if similar modifications occur in the productions of German speaking learners of French as a foreign language, we assessed learners’ speech through VOT duration measures in word-initial /p,t,k/. Data was collected through a reading-aloud elicitation task. Results provide support for the hypothesis that German native speakers are able to modify VOT duration when mimicking a French accent. Given these findings, we believe that accent imitation tasks could be used in L2 phonology instruction to raise learners’ awareness of non-distinctive phonetic differences.

Motor and visual influences on auditory neural processing during speaking and listening

Although previous research has documented the relationship between voice-onset time (VOT) and the production of foreign accent in English and Spanish, less is known about the role of this cue in perception. VOT refers to the aspiration that occurs between the release of a stop consonant and the beginning of the following segment. In Spanish and English, voiceless stop VOTs differ cross-linguistically in the duration of the aspiration. This study presents a quantitative analysis of VOT as it is associated with the degree of foreign accent perceived by 26 native speakers of Spanish and 160 native English speakers learning Spanish. The results show that both listener groups perceived and used VOT duration differences in their judgments of degree of foreign accent in Spanish, although nonnative listeners’ assessments varied according to their course enrollment. The findings suggest that language learners have a concept of what constitutes native-like Spanish and native-like VOTs in Spanish, information that they draw on in judging foreign accent. These results have implications for language instructors and adult language learners as well.

An investigation was made of the role of voice onset time (VOT) in distinguishing among Korean apical stop consonants. Measurements were made of VOT values for word-initial apical stops in the speech of four native Korean speakers. Words in citation form, in test sentences, in conversations among Korean adults, and in mothers' speech to children were used. Our results are not in accord with other experimenters who found complete separation of the aspirated from the strong and weak categories of Korean stops. VOT values for word-initial apical stops in the speech of all four speakers showed considerable overlap of the weak and aspirated categories. The strong and weak categories were also found to overlap, but the overlap in the weak and aspirated categories was greater. Our data suggest that although VOT is sufficient to distinguish the strong from the aspirated stops, it cannot effectively distinguish either of these from the weak stops. Our findings support Kim (1965), who proposes a feature of “tensity,” independent of VOT, to distinguish weak stops from the strong and aspirated stops of Korean.

Auditory cortical activity to different voice onset times in cochlear implant users

Production and perception of English stops by native Spanish speakers

Kinesthetic versus auditory cues in speech monitoring of post-lingual cochlear implant patients

The voicing distinction in English stop consonants involves distinct acoustic correlates depending on the position of the consonant. For Spanish speakers, prevocalic voicing distinction is in a familiar position whereas postvocalic voicing is in an unfamiliar position. In this study we examined whether Spanish speakers could use voice onset time and vowel duration to produce the voicing distinction in these two positions. Acoustic analysis showed Spanish speakers were able to produce the voicing distinction in both positions, although the magnitude of between-category difference is smaller compared to those produced by native English speakers. Production of the VOT distinction for prevocalic stops improved significantly following a brief tutorial on the acoustics of stop consonants, but the vowel duration difference for postvocalic stops did not show comparable change. These results suggest implementation of a phonological contrast in an unfamiliar position is constrained by native language characteristics. [Work supported by Ohio University College of Health Sciences and Professions Student Research Grant.]The voicing distinction in English stop consonants involves distinct acoustic correlates depending on the position of the consonant. For Spanish speakers, prevocalic voicing distinction is in a familiar position whereas postvocalic voicing is in an unfamiliar position. In this study we examined whether Spanish speakers could use voice onset time and vowel duration to produce the voicing distinction in these two positions. Acoustic analysis showed Spanish speakers were able to produce the voicing distinction in both positions, although the magnitude of between-category difference is smaller compared to those produced by native English speakers. Production of the VOT distinction for prevocalic stops improved significantly following a brief tutorial on the acoustics of stop consonants, but the vowel duration difference for postvocalic stops did not show comparable change. These results suggest implementation of a phonological contrast in an unfamiliar position is constrained by native language characteristic...

The purpose of this study was to compare stutterers' and nonstutterers' fluency during multiple productions of two dissimilar speech contexts. Twenty-two adult stutterers were matched within 1 year of age to 22 nonstutterers. Spectrographic analyses were performed on subjects' five consecutively fluent productions of a simple isolated phrase and a phrase extracted from an oral reading passage. Measures of fluent voice onset time (VOT), and vowel, consonant, and total phrase durations were calculated from the five repetitions of each phrase. From the isolated phrase, there were a total of five fluent durational measures (i.e., one VOT, two vowel, one consonant, & one phrase duration). For the phrase taken from the oral reading passage, six fluent measures were obtained (i.e., one VOT, three vowel, one consonant, & one phrase duration). Results demonstrated that only one of the five measurements taken during the isolated phrase condition was significantly different between the groups. Three of the six measures obtained from the phrase taken from the oral reading condition revealed significant between-group differences. No group differences were associated with the repetitions of either phrase for any of the dependent measures for both groups. These findings suggest that the length and complexity of the speech tasks used to obtain acoustic measures of stutterers' fluency play an important role in the discovery of differences between the fluency of the two groups.

ERP correlates of language-specific processing of auditory pitch feedback during self-vocalization

The effect of selective adaptation (i.e., listening to a rapidly repeated syllable) on the discrimination of voiceless stimuli which differ only in VOT was investigated. In an AX procedure under conditions of minimal stimulus uncertainty, subjects in the unadapted state were able to discriminate (d′=1)small (5 msec) differences in the VOT of stimuli from the voiceless end of a /ba/—/pa/ continuum. Control experiments showed this discrimination was not based on memorization of the aspiration noise waveform, and that subjects could represent small differences in VOT in long-term memory. Adaptation depressed discrimination slightly, showing that adaptation can affect a perceptual task which does not depend on phonetic categorization. The data were not precise enough to indicate whether adaptation affected a level sensitive to the acoustic similarity of the adapting and test stimuli or to the relationship of the adapting stimulus to the phonetic category.