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PubMed1999

Functional specialization of the human auditory cortex in processing phonetic and musical sounds: A magnetoencephalographic (MEG) study.

Functional specialization of the human auditory cortex in processing phonetic vs musical sounds was investigated. While subjects watched a silent self-selected movie, they were presented with sequences consisting of frequent and infrequent phonemes (/e/ and /o/, respectively) or chords (A major and A minor, respectively). The subjects' brain responses to these sounds were recorded with a 122-channel whole-head magnetometer. The data indicated that within the right hemisphere, the magnetoencephalographic (MEG) counterpart MMNm of the mismatch negativity (MMN) elicited by an infrequent chord change was stronger than the MMNm elicited by a phoneme change. Within the left hemisphere, the MMNm strength for a chord vs phoneme change did not significantly differ. Furthermore, the MMNm sources for the phoneme and chord changes were posterior to the P1m sources generated at or near the primary auditory areas. In addition, the MMNm source for a phoneme change was superior to that for the chord change in both hemispheres. The data thus provide evidence for spatially distinct cortical areas in both hemispheres specialized in representing phonetic and musical sounds.

Acoustic Stimulation↗
PubMed2002

Phonetic perception and the temporal cortex.

Recent functional neuroimaging studies have emphasized the role of the different areas within the left superior temporal sulcus (STS) for the perception of various speech stimuli. We report here the results of three independent studies additionally demonstrating hemodynamic responses in the vicinity of the planum temporale (PT). In these studies we used consonant-vowel (CV) syllables, tones, white noise, and vowels as acoustic stimuli in the context of whole-head functional magnetic resonance imaging, applying a long TR to attenuate possible masking effects by the scanner noise. To summarize, we obtained the following results for the contrasts comparing hemodynamic responses obtained during the perception of CV syllables compared to tones or white noise: (i) stronger activation in the vicinity of the left PT with two distinct foci of activation, one in a lateral position and the other more medial in the vicinity of Heschl's sulcus; (ii) stronger activation in the vicinity of the right PT; and (iii) stronger bilateral activation within the mid-STS. Further contrasts revealed the following findings: (iv) stronger bilateral activation to CV syllables than to vowels in the medial PT, (v) stronger left-sided activation to CV syllables than to vowels in the mid-STS, and (vi) stronger activation to CV syllables with voiceless initial consonants than to CV syllables with voiced initial consonants in the left medial PT. The results are compatible with the hypothesis that the STS contains neurons specialized for speech perception. However, these results also emphasize the role of the PT in the analysis of phonetic features, namely the voice-onset-time. Yet this does not mean that the PT is solely specialized for phonetic analysis. We hypothesize rather that the PT contains neurons specialized for the analysis of rapidly changing cues as was suggested by P. Tallal et al. (1993, Ann. N. Y. Acad. Sci. 682: 27-47).

Acoustic Stimulation↗
PubMed1980

Implications for phonetic symbolism: the relationship between pure tones and geometric figures.

In studies of phonetic symbolism, the most commonly cited attribute of speech relevant to the phenomenon has been frequency. The present study was conducted in order to examine the relationship between pure tone frequencies and geometric figures. A pure tone oscillator was constructed which produced tones in a continuous sweep from 4-12,250 Hz. Six geometric shapes were employed and varied along three binary dimensions (size, complexity, and density) producing a total of 48 stimulus figures. Twelve male and twelve female subjects adjusted pure tone frequencies until they "best fit" the visually presented geometric figure in a complete within-subject, block-randomization design of 48 trials. There was consistency in the assignment of pure tone frequencies to the dimensions of the geometric figures. Round figures (circles and ellipses) generally received lower frequency assignments than other figures, and the shape by size interaction was also found to be statistically significant. The results are interpreted in light of recent research in psycholinguistics and in particular to the hypothesis of a "universal phonetic symbolism".

Female↗
PubMed1981

Effects of phonetic distance on recognition of synthetic sentences.

Phonetic replacements for the syllable initial consonants and clusters of words in sentences were made according to the scale of phonetic distance devised by Black (Perceptual Differences Between Consonants. Columbus: The Ohio State University, 1974). The impact of such replacements upon the intelligibility of synthetically produced sentences was shown to be substantial. The regression of intelligibility over distance was strong, providing support for the construct validity of Black's scaling.

Female↗
PubMed1984

Production of /s/ as a function of word frequency, phonetic environment, and phoneme position.

The effects of word frequency, phonetic environment, and phoneme position on the production of /s/ in words by 50 phonologically impaired children were examined. Results indicated that: word frequency of occurrence did not significantly affect the rate of misarticulation; phonetic environments were significantly related to articulation errors; and positional variations were significantly different, prevocalic /s/ was easiest, followed by postvocalic and initial consonant clusters. These results are compared with previous studies, and the implications for management are discussed.

Articulation Disorders↗
PubMed1991

Phonatory and phonetic characteristics of prelinguistic vocal development in cri du chat syndrome.

A longitudinal case study of a child with cri du chat syndrome was undertaken to provide descriptive data on early phonatory and phonetic development in comfort state vocalizations. Vocal samples collected when the child was between 8 and 26 months of age were analyzed using perceptual and acoustic methods. Results indicated that the high vocal fundamental frequently documented in cries of infants with cri du chat syndrome was also a characteristic of comfort state vocalizations of this child. An analysis of intonation patterns indicated there was a predominance of falling intonation contours and limited interutterance variation of fundamental frequency. Phonetic development was quite delayed, with major acquisitions in babbling showing marked delay relative to chronological age. Acquisition of the first spoken word had not occurred by the age of twenty-six months. Results suggest that significant cognitive and/or motor delays may have an influence on the integrity of early vocal development, which calls into question the notion that babbling development proceeds relatively independently of other developmental domains.

Child, Preschool↗
PubMed1991

Serial processing and the "phonetic route:" lessons learned in the functional reorganization of deep dyslexia.

A patient with chronic agrammatic Broca's aphasia presented with symptoms of deep dyslexia, in which it is presumed that phonologic processing of the written message is disrupted. Functional reorganization of the "nonlexical" or phonetic route of reading was undertaken according to principles of A. R. Luria, whereby the patient must learn consciously to control behaviors that had formerly been unconscious and automatic. This patient's responses in treatment made it clear that the phonetic route encompasses at least two dissociable functions, grapheme-phoneme conversion and sequential analysis. This is discussed in light of Luria's ideas regarding the functions of the precentral and postcentral regions of sensori-motor cortex.

Adult↗
PubMed1983

Evoked potential indices of selective hemispheric engagement in affective and phonetic tasks.

Evoked potentials (EPs) to a probe click stimulus were recorded from left and right temporal areas of dextral adults engaged in phonetic and prosodic processing of an emotionally charged tape recorded conversation. Attenuation of the probe EP amplitudes was significantly greater in the left and right hemispheres during the phonetic and prosodic tasks, respectively, indicating lateral dominance shifts depending on selective processing of linguistic vs affective cues conveyed by the same speech signals.

Adult↗
PubMed1988

A case of foreign accent syndrome, with follow-up clinical, neuropsychological and phonetic descriptions.

We report a comparatively 'pure' case of 'foreign accent syndrome' (FAS) in a right-handed patient who sustained a small, isolated, left basal ganglia infarct. At 3 weeks post-onset FAS persisted in the absence of aphasic disorder. Phonetic analysis of the patient's speech was undertaken at that time and a further, more detailed acoustic and phonetic investigation, was undertaken at 8 months. The validity and significance of the term 'FAS' is discussed.

Adult↗
PubMed1988

Phonetically inaccurate spelling among learning-disabled, head-injured, and nondisabled young adults.

We applied the Boder and Jarrico (1982, The Boder Test of Reading-Spelling Patterns, New York: Grune & Stratton) criteria to the WRAT spelling list and examined the phonetically inaccurate spelling error patterns of learning-disabled (LD), head-injured (HI), and nondisabled young adults. Phonetically inaccurate (PI) errors were reliably rated (interrater r = .94) and were correlated significantly more strongly with dysphasic errors (r = .33) than with dyscopia (r = .16). ANOVA showed that LD and HI, which did not differ, made significantly more PI errors than both nondisabled and HI. These results indicate that PI errors reflect an underlying language disorder. The results also suggest that PI errors are more frequent in brain-related disorders. Finally, when group differences in cognitive ability are statistically controlled, PI errors are more common only among LD persons.

Achievement↗
PubMed1993

Glottal fry and voice disguise: a case study in forensic phonetics.

In recent legal proceedings, forensic phoneticians were called upon to analyse a tape-recorded message intended for the blackmail of a bank manager following the kidnap of his wife. The brief was to establish the likelihood that the tape recording may have been made by any one of three suspects, samples of whose speech were also made available. The comparison was greatly complicated by voice disguise employed by the speaker who recorded the kidnap tape. This disguise comprised a form of phonation described phonetically as 'glottal fry' or vocal 'creak'. This form of phonation occurs normally in normal speech, but it has received most attention in relation to voice pathologies. On the other hand there are few references to its use as a form of voice disguise. This paper discusses the nature of the creak, and examines its effectiveness as voice disguise. In addition, a method is described for speaker identification regardless of the disguise. Results indicate that trained listeners without repeated presentations or instrumentation are able to match speakers with 65% accuracy when one voice is creaky, compared with 90% accuracy for undisguised voices. Using a Euclidean metric to compare the power spectra of the [s] sound, we find that creaky disguised voices may be correctly matched with the undisguised voice of the same speaker (9 distracters) in 5 cases out of 10. However, when the computer's task is made more similar to the perceptual task, selecting one speaker out of two, it achieves an accuracy of 81%. Implications for forensic phonetics are discussed.

Crime↗
PubMed1990

Nasopharyngeal pressure gradients during non-phonetic activities of the velopharyngeal valve. Part II.

The subject of our study is the non-phonetic activities of the velopharyngeal valve (VPV). The VPVs of 10 patients were assessed by nasendoscopic examinations. The nasopharyngeal pressure fluctuations were recorded by catheters placed into the nasopharynx. Simultaneous pressure created in the oral cavity was measured as well. In Part I we discussed the swallowing activities and here we describe sucking and blowing activities. The pressure wave tracings and measurements with the nasendoscopic examination provide us with new information which permits a further study of the non-phonetic activity of the VPV and a correlation with its abnormal speech activity.

Adult↗
PubMed2002

Infant sensitivity to distributional information can affect phonetic discrimination.

For nearly two decades it has been known that infants' perception of speech sounds is affected by native language input during the first year of life. However, definitive evidence of a mechanism to explain these developmental changes in speech perception has remained elusive. The present study provides the first evidence for such a mechanism, showing that the statistical distribution of phonetic variation in the speech signal influences whether 6- and 8-month-old infants discriminate a pair of speech sounds. We familiarized infants with speech sounds from a phonetic continuum, exhibiting either a bimodal or unimodal frequency distribution. During the test phase, only infants in the bimodal condition discriminated tokens from the endpoints of the continuum. These results demonstrate that infants are sensitive to the statistical distribution of speech sounds in the input language, and that this sensitivity influences speech perception.

Attention↗
PubMed1983

Effects of phonetic similarity and order of report on the right ear advantage.

Two experiments are reported which were aimed at testing the effect of phonetic similarity and order of report on the right ear advantage in consonant-vowel dichotic tasks. The stimuli were consonant-vowel syllables which comprised the six stop consonants: /ba/, /da/, /ga/, /pa/, /ta/ and /ka/. In Experiment 1 the syllables were contrasted on place of articulation (condition 1) or on voicing (condition 2). In Experiment 2 the stimuli were contrasted either on one feature (place or voicing) or on both features (place and voicing). The results showed that the right ear advantage did not depend on phonetic similarity, whereas it depended on the order of report, being stronger when the perceptual channel was considered.

Adult↗
PubMed1987

Attentional capabilities of reading-impaired children during dichotic presentation of phonetic and complex nonphonetic sounds.

Reading-impaired boys, who were deficient in nonverbal auditory processing skills, were tested on their ability to identify a single speech sound (CV) when presented in dichotic competition with a nontarget CV or complex nonspeech sound (bleat). Sixteen reading-impaired boys aged 9 to 14 and 16 age-matched controls were presented with 30 CV-CV pairs and 30 CV-Bleat pairs. No difference was found between the two groups in their ability to identify the target CV, regardless of whether the competing stimulus was phonetic or nonphonetic. It was concluded that reading-impaired children of the type studied here are characterized more by an attentional capacity limitation than by an inability to focus attention or by a specific inability to process phonetic information.

Adolescent↗
PubMed2002

Mismatch negativity evoked by the McGurk-MacDonald effect: a phonetic representation within short-term memory.

OBJECTIVES: The McGurk-MacDonald illusory percept is obtained by dubbing an incongruent articulatory movement on an auditory phoneme. This type of audiovisual speech perception contributes to the assessment of theories of speech perception. The mismatch negativity (MMN) reflects the detection of a deviant stimulus within the auditory short-term memory and besides an acoustic component, possesses, under certain conditions, a phonetic one. The present study assessed the existence of an MMN evoked by McGurk-MacDonald percepts elicited by audiovisual stimuli with constant auditory components. METHODS: Cortical evoked potentials were recorded using the oddball paradigm on 8 adults in 3 experimental conditions: auditory alone, visual alone and audiovisual stimulation. Obtaining illusory percepts was confirmed in an additional psychophysical condition. RESULTS: The auditory deviant syllables and the audiovisual incongruent syllables elicited a significant MMN at Fz. In the visual condition, no negativity was observed either at Fz, or at O(z). CONCLUSIONS: An MMN can be evoked by visual articulatory deviants, provided they are presented in a suitable auditory context leading to a phonetically significant interaction. The recording of an MMN elicited by illusory McGurk percepts suggests that audiovisual integration mechanisms in speech take place rather early during the perceptual processes.

Acoustic Stimulation↗
PubMed1984

Perceptual-motor processing of phonetic features in speech.

Some reaction time experiments are reported on the relation between the perception and production of phonetic features in speech. Subjects had to produce spoken consonant-vowel syllables rapidly in response to other consonant-vowel stimulus syllables. The stimulus syllables were presented auditorily in one condition and visually in another. Reaction time was measured as a function of the phonetic features shared by the consonants of the stimulus and response syllables. Responses to auditory stimulus syllables were faster when the response syllables started with consonants that had the same voicing feature as those of the stimulus syllables. A shared place-of-articulation feature did not affect the speed of responses to auditory stimulus syllables, even though the place feature was highly salient. For visual stimulus syllables, performance was independent of whether the consonants of the response syllables had the same voicing, same place of articulation, or no shared features. This pattern of results occurred in cases where the syllables contained stop consonants and where they contained fricatives. It held for natural auditory stimuli as well as artificially synthesized ones. The overall data reveal a close relation between the perception and production of voicing features in speech. It does not appear that such a relation exists between perceiving and producing places of articulation. The experiments are relevant to the motor theory of speech perception and to other models of perceptual-motor interactions.

Adaptation, Physiological↗
PubMed1995

Lexical effects on phonetic categorization: the role of stimulus naturalness and stimulus quality.

A series of experiments was conducted to determine whether the effects of lexical status on phonetic categorization were influenced by stimulus naturalness (replicating M. W. Burton, S. R. Baum, & S. E. Blumstein, 1989, who manipulated the intrinsic properties of the stimuli) and by stimulus quality (presenting the stimuli in white noise). The experiments compared continua varying in voice onset time (VOT) only to continua covarying VOT and amplitude of the burst and aspiration noise in no-noise and noise conditions. Results overall showed that the emergence of a lexical effect was influenced by stimulus quality but not by stimulus naturalness. Contrary to previous findings, significant lexical effects failed to emerge in the slower reaction time ranges. These results suggest that stimulus quality contributes to lexical effects on phonetic categorization, whereas stimulus naturalness does not.

Adult↗