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PubMed2006

Infant-directed speech supports phonetic category learning in English and Japanese.

Across the first year of life, infants show decreased sensitivity to phonetic differences not used in the native language [Werker, J. F., & Tees, R. C. (1984). Cross-language speech perception: evidence for perceptual reorganization during the first year of life. Infant Behaviour and Development, 7, 49-63]. In an artificial language learning manipulation, Maye, Werker, and Gerken [Maye, J., Werker, J. F., & Gerken, L. (2002). Infant sensitivity to distributional information can affect phonetic discrimination. Cognition, 82(3), B101-B111] found that infants change their speech sound categories as a function of the distributional properties of the input. For such a distributional learning mechanism to be functional, however, it is essential that the input speech contain distributional cues to support such perceptual learning. To test this, we recorded Japanese and English mothers teaching words to their infants. Acoustic analyses revealed language-specific differences in the distributions of the cues used by mothers (or cues present in the input) to distinguish the vowels. The robust availability of these cues in maternal speech adds support to the hypothesis that distributional learning is an important mechanism whereby infants establish native language phonetic categories.

Canada↗
PubMed2006

Testing the protracted lexical restructuring hypothesis: the effects of position and acoustic-phonetic clarity on sensitivity to mispronunciations in children and adults.

Although developmental increases in the size of the position effect within a mispronunciation detection task have been interpreted as consistent with a view of the lexical restructuring process as protracted, the position effect itself might not be reliable. The current research examined the effects of position and clarity of acoustic-phonetic information on sensitivity to mispronounced onsets in 5- and 6-year-olds and adults. Both children and adults showed a position effect only when mispronunciations also differed in the amount of relevant acoustic-phonetic information. Adults' sensitivity to mispronounced second-syllable onsets also reflected the availability of acoustic-phonetic information. The implications of these findings are discussed in relation to the lexical restructuring hypothesis.

Acoustic Stimulation↗
PubMed2002

No effect of gender on tonal and phonetic mismatch negativity in normal adults assessed by a high-resolution EEG recording.

The auditory mismatch negativity (MMN) of event-related potential components has been widely used to assess the ability of auditory automatic change discrimination of verbal and nonverbal stimuli in healthy individuals and patients with various illnesses. To clarify the role of gender differences in the MMN, we compared the amplitude, latency, and topography of tonal and phonetic MMN between healthy males and females, using a high-density (128 channel) electroencephalography montage. The MMN was evaluated in 18 right-handed male and ten age-matched female adults. The MMN in response to a duration change of pure tone and that in response to a phonetic change (Japanese vowel /a/ versus /o/ with 150-ms duration) were recorded. There were no significant differences in amplitude, latency, or laterality for either tonal or phonetic MMN between male and female subjects. This lack of evidence for effects of gender on MMN in response to duration change of tones or that in response to changes of phonemes with a short duration in normal adults may be of relevance to a growing number of researchers who are studying the MMN in healthy individuals and various clinical groups.

Acoustic Stimulation↗
PubMed2003

Learning-induced neural plasticity associated with improved identification performance after training of a difficult second-language phonetic contrast.

Adult native Japanese speakers have difficulty perceiving the English /r-l/ phonetic contrast even after years of exposure. However, after extensive perceptual identification training, long-lasting improvement in identification performance can be attained. This fMRI study investigates localized changes in brain activity associated with 1 month of extensive feedback-based perceptual identification training by native Japanese speakers learning the English /r-l/ phonetic contrast. Before and after training, separate functional brain imaging sessions were conducted for identification of the English /r-l/ contrast (difficult for Japanese speakers), /b-g/ contrast (easy), and /b-v/ contrast (difficult), in which signal-correlated noise served as the reference control condition. Neural plasticity, denoted by exclusive enhancement in brain activity for the /r-l/ contrast, does not involve only reorganization in brain regions concerned with acoustic-phonetic processing (superior and medial temporal areas) but also the recruitment of additional bilateral cortical (supramarginal gyrus, planum temporale, Broca's area, premotor cortex, supplementary motor area) and subcortical regions (cerebellum, basal ganglia, substantia nigra) involved with auditory-articulatory (perceptual-motor) mappings related to verbal speech processing and learning. Contrary to what one may expect, brain activity for perception of a difficult contrast does not come to resemble that of an easy contrast as learning proceeds. Rather, the results support the hypothesis that improved identification performance may be due to the acquisition of auditory-articulatory mappings allowing for perception to be made in reference to potential action.

Brain↗
PubMed2002

Selective attention and the acquisition of new phonetic categories.

A class of selective attention models often applied to speech perception is used to study effects of training on the perception of an unfamiliar phonetic contrast. Attention-to-dimension (A2D) models of perceptual learning assume that the dimensions that structure listeners' perceptual space are constant and that learning involves only the reweighting of existing dimensions to emphasize or de-emphasize different sensory dimensions. Multidimensional scaling is used to identify the acoustic-phonetic dimensions listeners use before and after training to recognize the 3 classes of Korean stop consonants. Results suggest that A2D models can account for some observed restructuring of listeners' perceptual space, but listeners also show evidence of directing attention to a previously unattended dimension of phonetic contrast.

Attention↗
PubMed1980

Phonetic categorization in auditory word perception.

To investigate the interaction in speech perception of auditory information and lexical knowledge (in particular, knowledge of which phonetic sequences are words), acoustic continua varying in voice onset time were constructed so that for each acoustic continuum, one of the two possible phonetic categorizations made a word and the other did not. For example, one continuum ranged between the word dash and the nonword tash; another used the nonword dask and the word task. In two experiments, subjects showed a significant lexical effect--that is, a tendency to make phonetic categorizations that make words. This lexical effect was greater at the phoneme boundary (where auditory information is ambiguous) than at the ends of the condinua. Hence the lexical effect must arise at a stage of processing sensitive to both lexical knowledge and auditory information.

Discrimination Learning↗
PubMed1983

Visual and phonetic codes and the process of generation in letter matching.

Physically identical letter pairs are matched more quickly than are nominally identical or nonidentical pairs, which is an effect usually interpreted as resulting from the use of a visual memory code versus a phonetic or name code. However, prior manipulations of phonetic confusion and visual-field lateralization have provided little evidence consistent with this notion. Here, three reaction time experiments suggest through converging confusion and visual-field manipulations that a phonetic code is not used in either simultaneous or successive letter matching. Two additional experiments yield confusion evidence consistent with a rapid visual generation process underlying nominally identical and nonidentical matches, emphasizing the role of visual memory processes in all of the commonly used same-different letter-matching tasks. Implications for coding and hemispheric theories are discussed.

Form Perception↗
PubMed2001

Early phonetic and lexical development: a productivity approach.

Researchers frequently examine the development of the single-word lexicon in the absence of phonetic data. Yet a large body of literature demonstrates relationships between the phonetics of babble and early speech, and it is clear that production skill is essential for establishing a lexicon. This study uses longitudinal productivity criteria to establish children's phonetic skill. Twenty children were followed from age 9 to 16 months, and their level of consistency of vocal patterns was examined in relation to their lexical production, providing a relatively large-sample demonstration of phonetic/lexical relationships at the transition to language. Number of specific consonants produced consistently across the months of observation predicted referential lexical use at 16 months, whereas the transition to reference itself signaled the onset of a sharp increase in numbers of different words produced in a session. The earliest referential speakers exhibited prior consistency in the production of [p/b], which also predominated in their words. Prior use of at least two supraglottal consonants characterized the referential group. Children varied in the specific consonants they produced consistently, and these same consonants, varying according to individual child repertoire, characterized nearly all consonant-based words produced by each child in both of the final 2 months of observation. These findings are interpreted in relation to the children's contemporaneous development of representational ability and pragmatic skill.

Child Language↗
PubMed1981

Vocal tract control in Parkinson's disease: phonetic feature analysis of misarticulations.

Consonant articulation patterns of 200 Parkinson patients were defined by two expert listeners from high fidelity tape recordings of the sentence version of the Fisher-Logemann Test of Articulation Competence (1971). Phonetic transcription and phonetic feature analysis were the methodologies used. Of the 200 patients, 90 (45%) exhibited some misarticulations. Phonetic data on these 90 dysarthric Parkinson patients revealed articulatory errors highly consistent in detailed production characteristics. Manner changes predominated. Phoneme classes that were most affected were the stop-plosives, affricates, and fricatives. In terms of perception features (Chomsky & Halle, 1968), the stop-plosives and affricates, which are normally [-continuant] were produced as [+continuant] fricatives; fricatives that are [+strident] were produced as [-strident]. There is no implication, however, that Parkinsonism involves a perception deficit. Analysis of the articulatory deficit reveals inadequate tongue elevation to achieve complete closure on stop-plosives and affricates, which can be expressed in production features as a change from [+stop] to [+fricative]. There was also inadequate close constriction of the airway in lingual fricatives, which in articulatory features can be expressed as a change from [+fricative] to [-fricative]. Both the incomplete contact for stops and the partial constriction for fricatives represent an inadequate narrowing of the vocal tract at the point of articulation. These results are discussed in relation to recent EMG studies and other physiologic examinations of Parkinsonian dysarthria.

Electromyography↗
PubMed1997

Phonetic category structure of [I]: extent, best exemplars, and organization.

The current investigation examined the structure of the phonetic category [I] for 13 listeners. Experiments reported are results from identification, "best exemplar," and discrimination tasks using 105 [I] stimuli. The tokens were synthesized long a mel-spaced vowel continuum that differed in first and second formants. All stimuli ended in a 30 ms [b] sound. Results showed that 10 of 13 listeners demonstrated differing choices of the best exemplars, although most were within 37.5 mels of the central best exemplar chosen in the first experiment. Seven of the participants demonstrated "circular" patterns in identification of the [I] category that appeared to be organized around a central "best exemplar." Six participants showed other identification patterns: "downward," "upward," and "left-extending," with "best exemplars" on an edge or border of the phonetic categories. Graded category structure from a central "best exemplar" was apparent only in the averaged identification results, and not for individual participants. The size of the [I] category was significantly smaller than that surrounding the [i] best exemplar reported in a prior study by Sussman and Lauckner-Morano (1995). Finally, listeners had equivalent or better discrimination sensitivity with the best exemplar as the fixed standard compared to that for a "poor" exemplar token 45 mels away from the best exemplar. Results showed that phonetic category structure for the lax vowel [I] was different from the similar, but tense vowel [i]. The findings question whether prototype theory is generalizable to vowel categories other than [i].

Female↗
PubMed1998

Reprogramming phonologically similar utterances: the role of phonetic features in pre-motor encoding.

The effects of phonologic similarity on speech production latencies were investigated to explore the role of articulatory phonetic features and reprogramming operations during pre-motor stages of production. A form-based priming technique was used in five experiments to elicit rapid productions of single words. Subjects responded to visually presented pairs of minimally contrastive monosyllabic words, which varied with respect to the phonetic featural similarity of their onsets. Factors that were systematically manipulated across experiments included stimulus set size, duration of the interstimulus interval, and the use of feedback to subjects concerning their response latencies. Speech onset latencies obtained in a control condition in which no phonetic features were shared were compared to four other conditions in which the word initial phonemes of prime-target pairs did share features. Results revealed that shared manner was the most influential factor associated with the observed inhibitory phonologic similarity effect. In addition, smaller stimulus set size (6 words) yielded significantly slower overall response latencies than experiments employing larger stimulus sets (18 words). These findings suggested that inhibitory phonologic similarity effects did not stem from biomechanical constraints imposed by the articulatory system. Rather the methods employed in this investigation were supported as a means to investigate both the underlying units of representation and the processes involved in pre-motor planning apart from articulatory effects. The results of this investigation also supported the hypothesis that, during phonologic encoding, word form retrieval entails the selection and assembly of sublexical units into word form frames. No evidence of whole word retrieval during pre-motor encoding was obtained. The potential utility of this experimental paradigm in the investigation of pre-motor planning in disorders that putatively affect the processes involved in transforming word meaning into word form is also discussed.

Adult↗
PubMed1998

Real-time inflectional processing by children with specific language impairment: effects of phonetic substance.

In this study, we examined the processing of low-phonetic-substance inflections (e.g., third-person-singular -s, past-tense -ed) versus a higher-phonetic-substance inflection (e.g., present-progressive -ing) by children with specific language impairment (SLI) in two types of receptive tasks. Twenty-one children with SLI (Age: 8 years;6 months), 21 chronological age matched (CA; Age: 8;7), and 21 receptive syntax matched (RS; Age: 6;8) children participated in a word-recognition reaction time (RT) task and an off-line task requiring grammaticality judgments. On the RT task, the children with SLI demonstrated RT sensitivity only to the presence of a higher-phonetic-substance inflection, unlike the CA and RS controls who displayed sensitivity to both higher-substance and low-substance inflections. On the grammaticality judgment task, the children with SLI performed more poorly than the CA controls only on sentences missing obligatory low-substance inflections (e.g., "Carl already jump over the fence"). The findings are discussed within the framework of the surface account, which predicts that children with SLI should have greater difficulty processing and making grammatical judgments about low-substance inflections compared to higher-substance inflections.

Adolescent↗
PubMedDate not supplied

Learning and teaching phonetic transcription for clinical purposes.

This paper explores the theoretical issues surrounding clinical phonetic transcription which are pertinent to the education of speech and language therapy students. It draws on theoretical literature and practical experience, to consider issues of rationale, timing, structure, and content of courses in phonetic transcription for clinical purposes, and explores the problems and pitfalls inherent in the process. It is not a tutorial in clinical practical phonetics, but an examination of the issues which teachers of the subject need to consider in delivering such courses.

Humans↗
PubMed2005

Phonetic considerations in the design of voice assessment material.

A read text is commonly used in voice clinics for auditory perceptual evaluation of dysphonic voices and acoustic analysis. This paper examines the phonetic make-up of texts in several European languages to investigate their comparability in the frameworks of international, multi-lingual clinical studies, and the need for outcome measures in evidence-based practice. The preliminary work described investigates the complex notion of phonetic balancing. It shows that, despite very different phoneme inventories, certain similarities of sound-type usage appear cross-linguistically. Although this high level analysis is of interest and of potential practical use, because of linguistic and speaker-dependent contextual variation, more fine-grained phonetic and acoustic analyses are needed.

Humans↗
PubMed1989

Effects of alcohol on the acoustic-phonetic properties of speech: perceptual and acoustic analyses.

This report summarizes the results of a series of studies that examined the effects of alcohol on the acoustic-phonetic properties of speech. Audio recordings were made of male talkers producing lists of sentences under a sober condition and an intoxicated condition. These speech samples were then subjected to perceptual and acoustic analyses. In one perceptual experiment, listeners heard matched pairs of sentences from four talkers and were required to identify the sentence that was produced while the talker was intoxicated. In a second perceptual experiment, Indiana State Troopers and college undergraduates were required to judge whether individual sentences presented in isolation were produced in a sober or an intoxicated condition. The results of the perceptual experiments indicated that groups of listeners can significantly discriminate between speech samples produced under sober and intoxicated conditions. For acoustic analyses, digital signal processing techniques were used to measure acoustic-phonetic changes that took place in speech production when the talker was intoxicated. The results of the acoustical analyses revealed consistent and well-defined changes in speech articulation between sober and intoxicated conditions. Because speech production requires fine motor control and timing of the articulators, it may be possible to use acoustic-phonetic measures as sensitive indices of sensory-motor impairment due to alcohol consumption.

Adult↗
PubMed2001

Acoustic-phonetic features for the automatic classification of fricatives.

In this article, the acoustic-phonetic characteristics of the American English fricative consonants are investigated from the automatic classification standpoint. The features studied in the literature are evaluated and new features are proposed. To test the value of the extracted features, a statistically guided, knowledge-based, acoustic-phonetic system for the automatic classification of fricatives in speaker-independent continuous speech is proposed. The system uses an auditory-based front-end processing system and incorporates new algorithms for the extraction and manipulation of the acoustic-phonetic features that proved to be rich in their information content. Classification experiments are performed using hard-decision algorithms on fricatives extracted from the TIMIT database continuous speech of 60 speakers (not used in the design/training process) from seven different dialects of American English. An accuracy of 93% is obtained for voicing detection, 91% for place of articulation detection, and 87% for the overall classification of fricatives.

Algorithms↗
PubMed2003

Evaluating the function of phonetic perceptual phenomena within speech recognition: an examination of the perception of /d/-/t/ by adult cochlear implant users.

This study examined whether cochlear implant users must perceive differences along phonetic continua in the same way as do normal hearing listeners (i.e., sharp identification functions, poor within-category sensitivity, high between-category sensitivity) in order to recognize speech accurately. Adult postlingually deafened cochlear implant users, who were heterogeneous in terms of their implants and processing strategies, were tested on two phonetic perception tasks using a synthetic /da/-/ta/ continuum (phoneme identification and discrimination) and two speech recognition tasks using natural recordings from ten talkers (open-set word recognition and forced-choice /d/-/t/ recognition). Cochlear implant users tended to have identification boundaries and sensitivity peaks at voice onset times (VOT) that were longer than found for normal-hearing individuals. Sensitivity peak locations were significantly correlated with individual differences in cochlear implant performance; individuals who had a /d/-/t/ sensitivity peak near normal-hearing peak locations were most accurate at recognizing natural recordings of words and syllables. However, speech recognition was not strongly related to identification boundary locations or to overall levels of discrimination performance. The results suggest that perceptual sensitivity affects speech recognition accuracy, but that many cochlear implant users are able to accurately recognize speech without having typical normal-hearing patterns of phonetic perception.

Adult↗
PubMed2006

On phonetic convergence during conversational interaction.

Following research that found imitation in single-word shadowing, this study examines the degree to which interacting talkers increase similarity in phonetic repertoire during conversational interaction. Between-talker repetitions of the same lexical items produced in a conversational task were examined for phonetic convergence by asking a separate set of listeners to detect similarity in pronunciation across items in a perceptual task. In general, a listener judged a repeated item spoken by one talker in the task to be more similar to a sample production spoken by the talker's partner than corresponding pre- and postinteraction utterances. Both the role of a participant in the task and the sex of the pair of talkers affected the degree of convergence. These results suggest that talkers in conversational settings are susceptible to phonetic convergence, which can mark nonlinguistic functions in social discourse and can form the basis for phenomena such as accent change and dialect formation.

Adolescent↗