scholarly journals Auditory Cortex Accesses Phonological Categories: An MEG Mismatch Study

2000 ◽  
Vol 12 (6) ◽  
pp. 1038-1055 ◽  
Author(s):  
Colin Phillips ◽  
Thomas Pellathy ◽  
Alec Marantz ◽  
Elron Yellin ◽  
Kenneth Wexler ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Voice Onset Time ◽  
Brain Activity ◽  
Onset Time ◽  
Acoustic Parameter ◽  
Oddball Paradigm ◽  
Acoustic Discrimination ◽  
Phonological Categories ◽  
Show Evidence ◽  
The Many

The studies presented here use an adapted oddball paradigm to show evidence that representations of discrete phonological categories are available to the human auditory cortex. Brain activity was recorded using a 37-channel biomagnetometer while eight subjects listened passively to synthetic speech sounds. In the phonological condition, which contrasted stimuli from an acoustic /dæ/-/tæ/ continuum, a magnetic mismatch field (MMF) was elicited in a sequence of stimuli in which phonological categories occurred in a many-to-one ratio, but no acoustic many-to-one ratio was present. In order to isolate the contribution of phonological categories to the MMF responses, the acoustic parameter of voice onset time, which distinguished standard and deviant stimuli, was also varied within the standard and deviant categories. No MMF was elicited in the acoustic condition, in which the acoustic distribution of stimuli was identical to the first experiment, but the many-to-one distribution of phonological categories was removed. The design of these studies makes it possible to demonstrate the all-or-nothing property of phonological category membership. This approach contrasts with a number of previous studies of phonetic perception using the mismatch paradigm, which have demonstrated the graded property of enhanced acoustic discrimination at or near phonetic category boundaries.

Temporal Encoding of the Voice Onset Time Phonetic Parameter by Field Potentials Recorded Directly From Human Auditory Cortex

1999 ◽  
Vol 82 (5) ◽  
pp. 2346-2357 ◽  
Author(s):  
Mitchell Steinschneider ◽  
Igor O. Volkov ◽  
M. Daniel Noh ◽  
P. Charles Garell ◽  
Matthew A. Howard
Keyword(s):  
Auditory Cortex ◽  
Voice Onset Time ◽  
Onset Time ◽  
Stop Consonant ◽  
Superior Temporal Gyrus ◽  
Response Patterns ◽  
Stop Consonants ◽  
Field Potentials ◽  
Heschl’S Gyrus ◽  
Heschl's Gyrus

Voice onset time (VOT) is an important parameter of speech that denotes the time interval between consonant onset and the onset of low-frequency periodicity generated by rhythmic vocal cord vibration. Voiced stop consonants (/b/, /g/, and /d/) in syllable initial position are characterized by short VOTs, whereas unvoiced stop consonants (/p/, /k/, and t/) contain prolonged VOTs. As the VOT is increased in incremental steps, perception rapidly changes from a voiced stop consonant to an unvoiced consonant at an interval of 20–40 ms. This abrupt change in consonant identification is an example of categorical speech perception and is a central feature of phonetic discrimination. This study tested the hypothesis that VOT is represented within auditory cortex by transient responses time-locked to consonant and voicing onset. Auditory evoked potentials (AEPs) elicited by stop consonant-vowel (CV) syllables were recorded directly from Heschl's gyrus, the planum temporale, and the superior temporal gyrus in three patients undergoing evaluation for surgical remediation of medically intractable epilepsy. Voiced CV syllables elicited a triphasic sequence of field potentials within Heschl's gyrus. AEPs evoked by unvoiced CV syllables contained additional response components time-locked to voicing onset. Syllables with a VOT of 40, 60, or 80 ms evoked components time-locked to consonant release and voicing onset. In contrast, the syllable with a VOT of 20 ms evoked a markedly diminished response to voicing onset and elicited an AEP very similar in morphology to that evoked by the syllable with a 0-ms VOT. Similar response features were observed in the AEPs evoked by click trains. In this case, there was a marked decrease in amplitude of the transient response to the second click in trains with interpulse intervals of 20–25 ms. Speech-evoked AEPs recorded from the posterior superior temporal gyrus lateral to Heschl's gyrus displayed comparable response features, whereas field potentials recorded from three locations in the planum temporale did not contain components time-locked to voicing onset. This study demonstrates that VOT at least partially is represented in primary and specific secondary auditory cortical fields by synchronized activity time-locked to consonant release and voicing onset. Furthermore, AEPs exhibit features that may facilitate categorical perception of stop consonants, and these response patterns appear to be based on temporal processing limitations within auditory cortex. Demonstrations of similar speech-evoked response patterns in animals support a role for these experimental models in clarifying selected features of speech encoding.

scholarly journals Comparison of plosive sounds in monolingual and bilingual children, using the voice onset time acoustic parameter: cases report

Revista CEFAC ◽  
2018 ◽  
Vol 20 (5) ◽  
pp. 680-687
Author(s):  
Maria Teresa R. Lofredo-Bonatto ◽  
Marta A. Andrada e Silva
Keyword(s):  
Voice Onset Time ◽  
Onset Time ◽  
Acoustic Signals ◽  
Brazilian Portuguese ◽  
Acoustic Parameter ◽  
Bilingual Children ◽  
The Voice

ABSTRACT The purpose was to compare differences in production of plosive phonemes through the voice onset time (VOT) measurement in the speech of monolingual children, speakers of Brazilian Portuguese and bilingual children, speakers of both Brazilian Portuguese and English. The sample consisted of three monolingual children and three bilingual children; average age was 7 years. A speech emission was recorded for the investigation, which had the following vehicle phrase: “Diga ‘papa’ baixinho” (“Say ‘papa’ quietly”). Papa was then replaced by “baba”, “tata”, “dada”, “caca” and “gaga”. The measurements of the acoustic signals were performed through broadband spectrograms, and VOT was descriptively analyzed for the non-voiced sounds [p, t, k] and voiced [b, d, g] plosive sounds. Monolingual children presented higher average VOT values for [p, t, k] compared to bilingual children. For the [b, d, g] sounds, monolingual children had lower average VOT values, as compared to bilingual children. It was concluded that in the comparison of VOT measures of the speech samples, the monolingual children of Brazilian Portuguese presented higher values for the non voiced ones and lower for the voiced ones in relation to the bilingual children speakers of Brazilian Portuguese and English.

Phonetic drift reveals interconnected phonological representations in simultaneous bilinguals: A case study of English and Czech stop consonants

2020 ◽  
pp. 136700692093221
Author(s):  
Václav Jonáš Podlipský ◽  
Šárka Šimáčková ◽  
Kateřina Chládková
Keyword(s):  
Voice Onset Time ◽  
Onset Time ◽  
Target Language ◽  
Stop Consonants ◽  
Phonological Representations ◽  
Linear Mixed Effects ◽  
Phonological Categories ◽  
Language Exposure ◽  
Initial Target

Purpose: The interconnectedness of phonological categories between the two languages of early bilinguals has previously been explored using single-probe speech production and perception data. Our goal was to tap into bilingual phonological representations in another way, namely via monitoring instances of phonetic drift due to changes in language exposure. Design: We report a case study of two teenage English–Czech simultaneous bilinguals who live in Canada and spend summers in Czechia (Czech Republic). Voice onset time (VOT) of word-initial voiced and voiceless stops was measured upon the bilinguals’ arrival to and before their departure from a two-month stay in Czechia. Data and Analysis: Each bilingual read the same set of 71 Czech and 58 English stop-initial target words (and additional fillers) at each time of measurement. The measured VOT values were submitted to linear mixed effects models, assessing the effects of target language, measurement time, and underlying voicing. Findings/Conclusions: After the immersion in a Czech-speaking environment, for both speakers the count of voiced stops realized as prevoiced (i.e., having negative VOT) increased and the measured VOT of voiced stops (appearing different for English and Czech initially) drifted towards more negative (more Czech-like) values in both languages, while no change was detected for the voiceless stops of either English (aspirated) or Czech (unaspirated). The results suggest that the bilinguals maintain three-way VOT distinctions, differentiating voiceless aspirated (English), voiceless unaspirated (Czech), and voiced (English–Czech) stops, with connected bilingual representations of the voiced categories. Originality: Data on phonetic drift in simultaneous bilinguals proficient in their two languages have not previously been published. Significance/Implications: We show that observing phonetic shifts due to changes in the ambient linguistic environment can be revealing about the organization of phonological space in simultaneous bilinguals.

scholarly journals The production of the English stop voicing contrast by Arab L2 speakers of English

2020 ◽  
Vol 10 (2) ◽  
pp. 434-444
Author(s):  
Mohd Hilmi Hamzah ◽  
Ahmed Elsayed Samir Madbouly ◽  
Hasliza Abdul Halim ◽  
Abdul Halim Abdullah
Keyword(s):  
Native Speakers ◽  
Voice Onset Time ◽  
Onset Time ◽  
Initial Position ◽  
Acoustic Parameter ◽  
Voicing Contrast ◽  
Phonological Contrast ◽  
Fertile Ground ◽  
Voiceless Stop ◽  
Speech Learning

The English voiceless stop /p/ and voiced stop /ɡ/ are absent in the consonant inventory of Arabic. This difference provides a fertile ground for empirical research in L2 speech learning among Arab L2 speakers of English. The current study, therefore, aims to explore the English stop voicing contrast as produced by Arab native speakers. Focusing on Voice Onset Time (VOT) as an acoustic parameter, the study seeks to examine the extent to which (1) Arab L2 speakers of English maintain the English stop voicing contrast for /p-b/ and /k-ɡ/, and (2) the L2 VOT continuum by Arab L2 speakers follows or deviates from the L1 VOT continuum in English. The acoustic phonetic experiment involved elicited materials of /p-b/ and /k-ɡ/ from four male native speakers of Arabic. The tokens were recorded in isolation (utterance-initial position) and in a carrier sentence (utterance-medial position). The data were then acoustically analysed following standard segmentation, annotation and measurement criteria. Results reveal that the Arab L2 speakers can, to a large extent, maintain the English stop voicing contrast across all places of articulation, with voiced stops usually being produced with “normal” negative VOT (prevoicing) and voiceless stops usually being produced with “normal” positive VOT and also accompanied with aspiration in the long-lag region. There are also exceptional cases of “abnormal” negative VOT (prevoicing) for voiceless stops and “abnormal” positive VOT (devoicing) for voiced stops, with an extremely larger number of devoiced tokens for voiced stops in comparison to prevoiced tokens for voiceless stops. The results accord well with the Speech Learning Model’s prediction that phonetically “new” sounds are relatively easier to learn than phonetically “similar” sounds. The conclusion is drawn that languages sharing the same sound contrast may exhibit different phonetic implementations in marking a phonological contrast.

scholarly journals Transformation of a temporal speech cue to a spatial neural code in human auditory cortex

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Neal P Fox ◽  
Matthew Leonard ◽  
Matthias J Sjerps ◽  
Edward F Chang
Keyword(s):  
Auditory Cortex ◽  
Voice Onset Time ◽  
Onset Time ◽  
Neural Code ◽  
Neural Encoding ◽  
Spectral Cues ◽  
Temporal Cues ◽  
Neural Populations ◽  
Speech Cues ◽  
Simple Neural Network

In speech, listeners extract continuously-varying spectrotemporal cues from the acoustic signal to perceive discrete phonetic categories. Spectral cues are spatially encoded in the amplitude of responses in phonetically-tuned neural populations in auditory cortex. It remains unknown whether similar neurophysiological mechanisms encode temporal cues like voice-onset time (VOT), which distinguishes sounds like /b/ and/p/. We used direct brain recordings in humans to investigate the neural encoding of temporal speech cues with a VOT continuum from /ba/ to /pa/. We found that distinct neural populations respond preferentially to VOTs from one phonetic category, and are also sensitive to sub-phonetic VOT differences within a population’s preferred category. In a simple neural network model, simulated populations tuned to detect either temporal gaps or coincidences between spectral cues captured encoding patterns observed in real neural data. These results demonstrate that a spatial/amplitude neural code underlies the cortical representation of both spectral and temporal speech cues.

Speech-evoked activity in primary auditory cortex: effects of voice onset time

1994 ◽  
Vol 92 (1) ◽  
pp. 30-43 ◽  
Author(s):  
Mitchell Steinschneider ◽  
Charles E. Schroeder ◽  
Joseph C. Arezzo ◽  
Herbert G. Vaughan
Keyword(s):  
Auditory Cortex ◽  
Voice Onset Time ◽  
Onset Time ◽  
Primary Auditory Cortex ◽  
Evoked Activity
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