Individual talker differences in voice-onset-time: Contextual influences

Research has shown robust contextual influences on voice‐onset‐time (VOT) in speech production. The current work examines talker‐specificity for two such cases: speaking rate (VOT increases as syllable duration increases) and place of articulation (VOT increases as place moves from anterior to posterior position). Tokens of /pi/ (labial) and /ki/ (velar) were elicited from talkers across a range of rates. VOT and syllable duration were measured for each token. For each talker, separate labial and velar linear functions relating VOT to syllable duration were calculated. Ongoing analyses indicate that (1) for both the labial and velar functions there is significant variability across talkers’ slopes [see also Theodore et al., J. Acoust. Soc. Am. 120, 3293 (2006)], but there is no significant variability in the difference between labial and velar slopes for a given talker. Thus the effect of speaking rate is talker‐specific, and stable across place of articulation. (2) For each talker, the velar intercept is located at a longer VOT than the labial intercept, with significant variability in the magnitude of displacement across talkers. Thus the effect of place is also talker specific. These findings support the view that phonetic properties of speech include talker‐specific contextual influences. [Work supported by NIH/NIDCD.]

The aim of this paper is to determine the efficacy of Voice Onset Time (VOT) in distinguishing a series of word initial homorganic stop consonants in Shengologa, a dialect of Shekgalagarhi, a South-eastern Bantu language of the Western Sotho-Tswana group. Issues pertinent to VOT are also addressed: namely VOT as a function of place of articulation; and the effect of phonetic context on VOT; specifically the influence of the following vowel. Compared with other stops, ejectives have often manifested long VOT values in some languages with VOT values of around 80+ ms in duration being not uncommon. The argument is that in Shengologa, the voiceless unaspirated stops are pulmonic stops rather than glottalic. Voiceless aspirated stops in general manifest long duration of aspiration. LWATI: A Journal of Contemporary Research Vol.3 () 2006: pp.169-185

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.

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.

The ’’phoneme-boundary effect’’ refers to the observation that discrimination of stop consonants across a boundary between phoneme categories is superior to discrimination of comparable stimulus differences within a phoneme category. The present experiment employed signal detection methodology (a) to distinguish between changes in discriminability and response bias; and (b) to reevaluate the role of phonetic categorization in the phoneme-boundary effect. A SAME–DIFFERENT discrimination task compared discrimination of 10− and 20−msec differences in voice onset time (VOT) in a synthetic stimulus continuum ranging from [ba] to [pa] (VOT’s from −50 to +70 msec). Both a clear increase in discriminability and a marked shift in response bias from SAME to DIFFERENT occurred near the voiced–voiceless boundary. When variations in VOT were isolated from syllable context so that they were not categorized as phonemes, discriminability increased near the voiced–voiceless boundary in a manner comparable to the full-syllable stimuli. These data suggest that the phoneme-boundary effect in VOT discrimination reflects a genuine increase in discriminability near the phoneme boundary. However, in agreement with the recent data of J. D. Miller and his colleagues, these results suggest further that the phoneme-boundary effect for VOT is not due exclusively to phonetic categorization but may instead reflect acoustic and auditory properties which are distinct from phonetic processing. Subject Classification: [43]70.30; [43]65.75; [43]70.35..

The present study aims to investigate, through acoustic analysis, the acquisition of voicing contrast in Hungarian word-initial bilabial and alveolar stops (p/b and t/d) produced by 15 children with primary language disorders between 5;6 and 7;7 years of age. Data collection was based on a picture-naming task involving at least four different pictures for each segment tested. The elicited data were audio-recorded and then evaluated in terms of the proportion of pre-voiced stops per target category, the duration of voice onset time (VOT), and the presence of other phonetic features. The results revealed that, while all target voiceless stops are produced without pre-voicing, there is a bimodal distribution of VOTs for target voiced categories. Regarding the duration of VOTs, accurate realisations show average VOTs of immature values, and no sub-phonemic level differences were revealed in the distribution of VOTs for inaccurate realisations. Furthermore, voiceless realisations present frequently double/multiple release bursts. Findings are discussed in relation to a study on VOT distribution in the speech of typically developing children and to suggestions for further investigations.

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.

Training to use voice onset time as a cue to talker identification induces a left-ear/right-hemisphere processing advantage

The assumption that listeners are unaware of the highly encoded acoustic properties which lead to phoneme identification is questioned in the present study. It was found that some subjects can make use of small differences in voice onset time when making within-category discriminations. Subjects who can use these auditory features do so both implicitly (in a phonetic match task) and deliberately (in a physical match task). Results also indicate that some type of parallel process model is needed to account for the processing of auditory and phonetic information.

Voice onset time is known to be affected by phonetic context, age, native language of the speaker, or presence of a communication disorder in the speaker. The role of gender in VOT production has not been investigated. The present study reports a significant gender difference in VOT production of the /d/ and /t/ stops, with men having shorter VOTs than women ( n subjects = 16). Qualitative differences in VOT based on gender are also noted. Although a significant difference in speaking rate between the genders was found, this was not correlated with VOT. Gender differences in VOT have implications for other research.

The study investigates voice onset time (VOT) in German stop consonants and its relationship to place of articulation in a variety of phonetic environments. The outstanding findings are the consistently lowest values for the alveolars and the particular susceptibility of the VOT of bilabials to environmental variables like position in the utterance and stress. Highest values for velar stops are only achieved in initial position and medially before stress. Airflow measurements suggest a direct relationship between VOT and rate of articulation and airflow.

Second language (L2) production can be a kind of interlanguage, a relatively stable system bearing the nature of both the native language (L1) and L2. Within such a system sound components of a syllable may bear their own interlanguage characteristics and yet interact with the other component sounds. The present study investigates temporal patterns of L1–L2 interaction at the syllable level. Audio recordings were made of English stop-vowel syllables produced by native speakers of Mandarin who were fluent in English (ChE). Native English productions (AmE) of these syllables and native productions of Mandarin (ChM) stop-vowel syllables were acquired as native norms. Temporal measures included stop closure duration, voice-onset time (VOT), vowel duration, and syllable duration. Results show that the internal timing components of ChE often deviate from AmE, with the closure duration, VOT, and vowel duration being intermediate to AmE and ChM. However, at the syllable level, ChE productions tend to follow the overall patterns of AmE. Temporal deviations were often compensated by temporal compensation of other components in the syllable, maintaining a balanced consonant/vowel distribution. These findings have implications for a broader understanding of L2 productions.

As part of an ongoing study of talker-specific speech processing, we sought to document the existence of individual talker differences in voice-onset-time (VOT). Four female and four male talkers, all native speakers of American English, were asked to produce 30 repetitions each of 18 different words beginning with /p/, /t/, or /k/. Words were displayed visually on a computer monitor one at a time in a randomized order at a constant presentation rate, and talkers were asked to produce the words at a comfortable speaking rate. The VOT and duration of each spoken word were measured. The eight talkers showed substantial individual variation in speaking rate (as measured by word duration) and, as would be expected, slower speaking rates were associated with longer VOT values. In order to determine whether there were individual differences in VOT beyond those associated with speaking rate, we conducted analyses that controlled for speaking rate on a word-by-word basis. These analyses revealed cases of consistent individual differences in VOT. We are currently examining whether the structure of listeners’ perceptual voicing categories reflects such individual talker differences. [Work supported by NIH/NIDCD.]

This paper presents an acoustic analysis of Voice Onset Time (VOT) in oral stop consonants in Blackfoot, an Algonquian language without contrastive voicing. We focus on VOT as one of the key temporal acoustic correlates of voicing and investigate VOT variation in relation to (i) place of articulation (labial vs. alveolar vs. velar); (ii) length (long vs. short), quality (/a/ vs. /o/), and accent pattern (accented vs. unaccented) of the following vowel; (iii) word position (initial vs. medial); (iv) gender; and (v) age. We analyzed 2096 stop consonant tokens produced by 13 participants, who completed two different tasks: an English-to-Blackfoot translation task and a picture naming task. The key findings are as follows: (i) Blackfoot stop consonants fall into the short-lag range that overlaps with the English voiced category, with mean VOT values ranging from 11.6–32.7 ms; (ii) VOT values become progressively longer as the place of articulation moves to more posterior positions; (iii) VOT values are longer before high vowels than before low vowels; (iv) VOT values are longer before long vowels than before short vowels; (v) no statistically significant effect was found for the linguistic factors word position and accent pattern; (vi) no statistically significant effect was found for the socio-indexical factors age and gender; and (vii) no statistically significant effect was found for the experimental factor task type. The implications of our findings for the Blackfoot writing system and ongoing work on language documentation and revitalization are briefly discussed.

The Georgian stop system has a three-way opposition: voiced, voiceless aspirated, and voiceless ejective. This paper reports on results from an analysis of voice onset time (VOT) in word-initial stop consonants preceding /a/. Two native speakers of Georgian (one male, one female) were recorded reading two randomized token lists: one containing nonsense syllables (e.g., ‘‘ba’’) and one containing actual Georgian words (e.g., ‘‘balaxi’’ ‘‘grass’’). Tokens were repeated twice. VOT values were measured using spectrograms and waveforms. Results show that VOT clearly distinguishes two categories in Georgian: voiced and voiceless. Initial voiced stops had short positive VOTs, while the initial voiceless stops had relatively long positive VOT values. Within the voiceless category, however, mean VOT values for ejectives and aspirates overlapped. Articulatory and acoustic characteristics of ejectives and aspirates are discussed in relation to other possible cues for distinguishing between the two types of stops. In addition to stop categories, the results show a trend toward another distinction: place of articulation. Labials had the lowest VOT values, followed by coronals, and then velars. The results from these analyses are compared to studies of voice onset time in other languages.