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PubMed1997

Talker identification based on phonetic information.

Accounts of the identification of words and talkers commonly rely on different acoustic properties. To identify a word, a perceiver discards acoustic aspects of an utterance that are talker specific, forming an abstract representation of the linguistic message with which to probe a mental lexicon. To identify a talker, a perceiver discards acoustic aspects of an utterance specific to particular phonemes, creating a representation of voice quality with which to search for familiar talkers in long-term memory. In 3 experiments, sinewave replicas of natural speech sampled from 10 talkers eliminated natural voice quality while preserving idiosyncratic phonetic variation. Listeners identified the sinewave talkers without recourse to acoustic attributes of natural voice quality. This finding supports a revised description of speech perception in which the phonetic properties of utterances serve to identify both words and talkers.

Adult↗

PubMed1997

On prototypes and phonetic categories: a critical assessment of the perceptual magnet effect in speech perception.

According to P. K. Kuhl (1991), a perceptual magnet effect occurs when discrimination accuracy is lower among better instances of a phonetic category than among poorer instances. Three experiments examined the perceptual magnet effect for the vowel /i/. In Experiment 1, participants rated some examples of /i/ as better instances of the category than others. In Experiment 2, no perceptual magnet effect was observed with materials based on Kuhl's tokens of /i/ or with items normed for each participant. In Experiment 3, participants labeled the vowels developed from Kuhl's test set. Many of the vowels in the nonprototype /i/ condition were not categorized as /i/s. This finding suggests that the comparisons obtained in Kuhl's original study spanned different phonetic categories.

Analysis of Variance↗

PubMed1981

How the components of speaking rate influence perception of phonetic segments.

In two studies we investigated the way in which the components of speaking rate, articulation rate and pause rate, combine to influence processing of the silence-duration cue for the voicing distinction in medial stop consonants. First, we replicated the finding that the articulation rate of a carrier sentence, that is, the rate at which the speech itself is produced, influences how the duration information is used to assign voicing values. Second, and more importantly, the assignment of voicing values was also influenced by the pause rate of the sentence. Thus, the listener adjusts for both articulation rate and pause rate when processing the phonetically relevant information. Finally, the two rate components did not function in an equivalent manner, since changes in articulation rate had considerably more effect on phonetic judgments than did changes in pause rate. Alternative explanations fo the relative weighting of the two variables are discussed.

Humans↗

PubMed1982

Context independence and phonetic mediation in categorical perception.

Categorical perception, as an ideal situation, is rarely if ever observed in the laboratory. Two separate requirements must be met for categorical perception: (a) Discrimination performance must be phonetically mediated (i.e., it should be predictable from labeling performance), (b) labeling responses must be independent of the stimulus context. To determine the extent to which departures from the ideal are due to failures to meet one or both of these requirements, we used four stimulus continua in same-different (AX) discrimination and labeling tasks: stop-consonant-vowel (CV) syllables, isolated vowels, isolated fricative noises, and nonspeech sounds varying in timbre. We found that perception of CV syllables fell short of the ideal only because of contextual influences on labeling. Neither criterion of categorical perception was met by vowels or fricative noises, but subjects were more prone to phonetic mediation with vowels than with fricative noises, and they showed more context independence with fricative noises than with vowels. Surprisingly, the nonspeech timbre stimuli satisfied both requirements better than either vowels or fricative noises. This findings was attributed to the short duration of our timbre stimuli, which prevented them from sounding vowel-like but at the same time may have prevented stable auditory memory traces.

Discrimination Learning↗

PubMed1993

Phonetic recoding of phonologically ambiguous printed words.

Speech detection and matching simultaneously presented printed and spoken words were used to examine phonologic and phonetic processing of Hebrew heterophonic homographs. Subjects detected a correspondence between an ambiguous letter string and the amplitude envelopes of both dominant and subordinate phonological alternatives. Similar effects were obtained when the homographs were phonologically disambiguated by adding vowel marks. The matching of the unpointed printed forms of heterophonic homographs to the dominant and subordinate spoken alternatives presented auditorily was as fast as matching the pointed unambiguous forms to the respective spoken words. This outcome was not obtained when print and speech were not presented simultaneously. These results suggest that printed heterophonic homographs activate the two spoken alternatives they represent and provide further confirmation for fast phonetic recoding in reading.

Acoustic Stimulation↗

PubMed2004

Vowel duration affects visual word identification: evidence that the mediating phonology is phonetically informed.

What form is the lexical phonology that gives rise to phonological effects in visual lexical decision? The authors explored the hypothesis that beyond phonological contrasts the physical phonetic details of words are included. Three experiments using lexical decision and 1 using naming compared processing times for printed words (e.g., plead and pleat) that differ, when spoken, in vowel length and overall duration. Latencies were longer for long-vowel words than for short-vowel words in lexical decision but not in naming. Further, lexical decision on long-vowel words benefited more from identity priming than lexical decision on short-vowel words, suggesting that representations of long-vowel words achieve activation thresholds more slowly. The discussion focused on phonetically informed phonologies, particularly gestural phonology and its potential for understanding reading acquisition and performance.

Humans↗

PubMed2004

The influence of multiple presentations on judgments of children's phonetic accuracy.

Two experiments examined whether listening to multiple presentations of recorded speech stimuli influences the reliability and accuracy of judgments of children's speech production accuracy. In Experiment 1, 10 listeners phonetically transcribed words produced by children with phonological impairments after a single presentation and after the word was played 7 times. Inter- and intratranscriber reliability in the single- and multiple-presentation conditions did not differ significantly. In Experiment 2, 18 listeners provided binary correct/incorrect judgments of /s/ accuracy in single- and multiple-presentation conditions. There was no systematic effect of presentation condition on either accuracy or intrarater reliability. However, greater interrater reliability was noted in the multiple-presentation condition, particularly for tokens of /s/ that were incorrect or acoustically intermediate between an incorrect and a correct /s/. Taken together, the results suggest that multiple presentations have no measurable effect on the accuracy and intrarater reliability of judgments of children's phonetic accuracy, but that they do have a small effect on interrater reliability. Clinical implications are discussed.

Adult↗

PubMed2006

A weighted reliability measure for phonetic transcription.

PURPOSE: The purpose of the present work is to describe and illustrate the utility of a new tool for assessment of transcription agreement. Traditional measures have not characterized overall transcription agreement with sufficient resolution, specifically because they have often treated all phonetic differences between segments in transcriptions as equivalent, thus constituting an unweighted approach to agreement assessment. The measure the authors have developed calculates a weighted transcription agreement value based on principles derived from widely accepted tenets of phonological theory. METHOD: To investigate the utility of the new measure, 8 coders transcribed samples of speech and infant vocalizations. Comparing the transcriptions through a computer-based implementation of the new weighted and the traditional unweighted measures, they investigated the scaling properties of both. RESULTS: The results illustrate better scaling with the weighted measure, in particular because the weighted measure is not subject to the floor effects that occur with the traditional measure when applied to samples that are difficult to transcribe. Furthermore, the new weighted measure shows orderly relations in degree of agreement across coded samples of early canonical-stage babbling, early meaningful speech in English, and 3 adult languages. CONCLUSIONS: The authors conclude that the weighted measure may provide improved foundations for research on phonetic transcription and for monitoring of transcription reliability.

Humans↗

PubMed1987

Phonetic development in identical twins differing in auditory function.

The subjects of this report are identical (monozygotic) twin boys who differ in auditory function. One has normal hearing; the other has a profound hearing loss bilaterally. These boys offered a rare opportunity to study the effects of hearing loss on vocal development with reasonable control over environmental and genetic factors. This initial report focuses on their vocal development over the sampled ages of 8, 12, and 15 months. Acoustic-phonetic differences in the babbling of the two boys were evident in the 8-month sample (the first recording opportunity), and some differences between them became greater over the succeeding samples at 12 and 15 months. The major differences were in the formant patterns of vocalic elements; the frequency of occurrence of fricatives, affricates, and trills; histograms of syllable type; and variation in vowel usage. The data hold implications for the early identification of infants at risk for communication disorder and for the understanding of auditory-motor processes in phonetic development during infancy.

Child Language↗

PubMed1989

Toward phonetic intelligibility testing in dysarthria.

The measurement of intelligibility in dysarthric individuals is a major concern in clinical assessment and management and in research on dysarthria. The measurement objective is complicated by the fact that intelligibility is not an absolute quantity but rather a relative quantity that depends on variables such as test material, personnel, training, test procedures, and state of the speaker. This paper reviews scaling procedures and item identification tests as they have been applied to dysarthric speech. Based in part on previous studies of speech of the hearing impaired, a profile has been designed to direct research on the acoustic or physiologic correlates of dysarthric intelligibility impairment. In addition, a word intelligibility test is proposed for use with dysarthric speakers. This test is designed to examine 19 acoustic-phonetic contrasts that are likely to (a) be sensitive to dysarthric impairment and (b) contribute significantly to speech intelligibility. Preliminary data from a sample of subjects with amyotrophic lateral sclerosis are presented to illustrate the use of this test in the phonetic interpretation of intelligibility impairment.

Adult↗

PubMed1984

A procedure for phonetic transcription by consensus.

A consensus transcription procedure is presented, and representative data are reported. The procedure includes explicit response definitions for mapping narrow phonetic transcription onto dichotomous, nonerror/error scores and 17 rules for obtaining consensus between two transcribers. The data include descriptive statistics for consensus rule use based on over 18,000 sounds transcribed during a normative study of speech sound acquisition in children aged 3-6 years. Validity and reliability issues in phonetic transcription are discussed.

Child↗

PubMed1987

Contrastive stress, phonetic context, and misarticulation of /r/ in young speakers.

The purpose of this study was to examine the effects of contrastive stress and phonetic context on misarticulations of consonantal /r/. Subjects were 9 children between the ages of 4:5 (years:months) and 5:7 who exhibited normal articulation development but inconsistently misarticulated /r/. The experimental task was designed to elicit consonantal /r/ in two phonetic contexts ([rV] & [CrV]) and two stress conditions (primary & nonprimary stress). Three listeners who were naive to the experimental hypotheses judged the children's productions for accuracy of /r/ production and for stress. Significant main effects were obtained for context and stress: /r/ productions were more often judged as correct in clusters than in singletons and in words not receiving primary stress than in words receiving primary stress. Results are discussed in terms of the possible effects of production and perceptual variables on listener judgments. Inferences are drawn concerning future research on speaker and listener effects in the study of articulation.

Articulation Disorders↗

PubMed1991

Interobserver reliability using the Phonetic Level Evaluation with severely and profoundly hearing-impaired children.

This study examines whether observers reliably categorize selected speech production behaviors in hearing-impaired children. A group of experienced speech-language pathologists was trained to score the elicited imitations of 5 profoundly and 5 severely hearing-impaired subjects using the Phonetic Level Evaluation (Ling, 1976). Interrater reliability was calculated using intraclass correlation coefficients. Overall, the magnitude of the coefficients was found to be considerably below what would be accepted in published behavioral research. Failure to obtain acceptably high levels of reliability suggests that the Phonetic Level Evaluation may not yet be an accurate and objective speech assessment measure for hearing-impaired children.

Analysis of Variance↗

PubMed1995

Activation of lip motor units with variations in speech rate and phonetic structure.

The purpose of this study was to describe the activation characteristics of lip-muscle single motor units in relation to speech rate and phonetic structure. Repeated experiments were carried out on three adult subjects from whom recordings of lower lip EMG and two-dimensional displacement were obtained. Single motor unit recordings were obtained from the orbicularis oris inferior (OOI), depressor labii inferior (DLI), and mentalis (MENT) muscles. Subjects' tasks involved repeating CV syllables at 1 to 4 syllables per second (syl/sec). The distribution of interspike intervals and corresponding firing rates were obtained on 11 motor units. The firing rates of OOI and MENT motor units increased as syllable rate changed from 1 to 3 syl/sec, but firing rates tended to be equivalent at 3 and 4 syl/sec. DLI and tonic motor units showed little or no modulation in their firing rates with speech rate. Firing rate data and related observations on lip movement and EMG spike count levels suggest that distinct neuromechanical processes control lip movements at low and high speech rates. Both kinematic and EMG data support the expectation that phonetic structure has its greatest effects on lip opening compared to lip closing movements in CV syllables. OOI and MENT activation levels tended to be highest for /p/ productions compared to /w/ and /f/. This may be related to the requirements for complete lip closure and elevated levels of intraoral pressure for production of /p/.

Adult↗

PubMed1999

A 4-year investigation into phonetic inventory development in young cochlear implant users.

Phonetic inventories of 9 children with profoundly impaired hearing who used the 22-electrode cochlear implant (Cochlear Limited) were monitored before implantation and during the first 4 years of implant use. All children were 5 years old or younger at the time of implant. Spontaneous speech samples were collected at regular intervals for each child and analyzed to investigate phone acquisition over the post-implant period. Acquisition was measured using two different criteria. The "targetless" criterion required the child to produce a phonetically recognizable sound spontaneously, and the "target" criterion required the child to produce the phone correctly at least 50% of the time in meaningful words. At 4 years post-implant, 40 out of 44 phones (91 %) had reached the targetless criterion, and 29 phones (66%) had reached the target criterion for 5 or more of the children. Over the time of the study 100% of monophthongs, 63% of diphthongs, and 54% of consonants reached the target criterion. The average time taken for a phone to progress from the targetless to target criterion was 15 months. Overall, the data suggest trends in the order of phone acquisition similar to those of normally hearing children, although the process of acquisition occurred at a slower rate.

Child, Preschool↗

PubMed2000

Perceptual-phonetic predictors of single-word intelligibility: a study of Cantonese dysarthria.

This study investigated the perceptual-phonetic predictors of intelligibility in Cantonese speakers with dysarthria. The speakers were 20 young adults with cerebral palsy. The listener group consisted of 12 native Cantonese speakers. A single-word intelligibility test was constructed, based on 17 phonetic contrasts. There were no significant differences in intelligibility for gender, age, or type of cerebral palsy. A regression analysis showed that intelligibility could be predicted with 97% accuracy by 5 out of the 6 most problematic contrasts. Three contrasts (glottal vs. null, final vs. null, and long vs. short vowel) predicted variation on an independent intelligibility measure obtained for the same speakers with 84% accuracy. Principal components analysis derived 4 components, which accounted for 81% of the variance in the 17 contrasts. Physiological explanations and language-specific contributions to speech disorder in this group of speakers are discussed.

Adolescent↗

PubMed1999

Human brain specialization for phonetic attention.

The effects of auditory selective attention on event related potentials (ERPs) to speech sounds were examined in subjects attending to vowel-consonant-vowels (VCVs) in one ear while ignoring VCVs in the opposite ear. In one condition, subjects discriminated phonetic changes in the VC, CV, or both formant-transition regions. In another condition, they discriminated equally difficult intensity changes in the same VCV regions. Attention-related negative difference waves showed enhanced early and late components (Nde and Ndl) during phoneme-discrimination conditions. Hemispheric asymmetries developed only during the Ndl and were more pronounced during phoneme discrimination. The results suggest that auditory areas of both hemispheres are specialized for phonetic analysis, with hemispherically specialized mechanisms engaged primarily during the final stages of phoneme processing.

Adult↗

PubMed1999

Similarity as a risk factor in drug-name confusion errors: the look-alike (orthographic) and sound-alike (phonetic) model.

BACKGROUND: One of every four medication errors reported in the United States is a name-confusion error. The rate of name-confusion errors might be reduced if new and confusing names were not allowed on the market and if safeguards could be put in place to avoid confusion between existing names. OBJECTIVES: To evaluate several prognostic tests of drug-name confusion, alone and in combination, with respect to their sensitivity, specificity, and overall accuracy. RESEARCH DESIGN: Case-control study. Twenty-two different computerized measures of orthographic similarity, orthographic distance, and phonetic similarity were used to compute similarity/distance scores for n = 1,127 cases (ie, pairs of names that appeared in published error reports or national error databases) and n = 1,127 controls. MAIN OUTCOME MEASURES: Mean similarity/distance scores were compared across cases and controls. The performance of each measure at distinguishing between cases and controls was evaluated by tenfold crossvalidation. Dose-response relationships were examined. Univariate and multivariate logistic regression models were formed and evaluated by 10 fold crossvalidation. RESULTS: Cases had significantly higher similarity scores than controls. Every measure of similarity proved to be a significant risk factor for error. There was a significant increasing trend in the odds-ratio as a function of similarity. A three-predictor logistic regression model had crossvalidated sensitivity of 93.7%, specificity of 95.9% and accuracy of 94.8%. CONCLUSIONS: A sensitive and specific test of drug-name confusion potential can be formed using objective measures of orthographic similarity, orthographic distance, and phonetic distance.

Analysis of Variance↗