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PubMed2006

Temporal properties in clear speech perception.

Three experiments were conducted to study relative contributions of speaking rate, temporal envelope, and temporal fine structure to clear speech perception. Experiment I used uniform time scaling to match the speaking rate between clear and conversational speech. Experiment II decreased the speaking rate in conversational speech without processing artifacts by increasing silent gaps between phonetic segments. Experiment III created "auditory chimeras" by mixing the temporal envelope of clear speech with the fine structure of conversational speech, and vice versa. Speech intelligibility in normal-hearing listeners was measured over a wide range of signal-to-noise ratios to derive speech reception thresholds (SRT). The results showed that processing artifacts in uniform time scaling, particularly time compression, reduced speech intelligibility. Inserting gaps in conversational speech improved the SRT by 1.3 dB, but this improvement might be a result of increased short-term signal-to-noise ratios during level normalization. Data from auditory chimeras indicated that the temporal envelope cue contributed more to the clear speech advantage at high signal-to-noise ratios, whereas the temporal fine structure cue contributed more at low signal-to-noise ratios. Taken together, these results suggest that acoustic cues for the clear speech advantage are multiple and distributed.

Analysis of Variance↗
PubMed1997

Speech perception deficits in poor readers: auditory processing or phonological coding?

Poor readers are inferior to normal-reading peers in aspects of speech perception. Two hypotheses have been proposed to account for their deficits: (i) a speech-specific failure in phonological representation and (ii) a general deficit in auditory "temporal processing," such that they cannot easily perceive the rapid spectral changes of formant transitions at the onset of stop-vowel syllables. To test these hypotheses, two groups of second-grade children (20 "good readers," 20 "poor readers"), matched for age and intelligence, were selected to differ significantly on a /ba/-/da/ temporal order judgment (TOJ) task, said to be diagnostic of a temporal processing deficit. Three experiments then showed that the groups did not differ in: (i) TOJ when /ba/ and /da/ were paired with more easily discriminated syllables (/ba/-/sa/, /da/-/fa/); (ii) discriminating nonspeech sine wave analogs of the second and third formants of /ba/ and /da/; (iii) sensitivity to brief transitional cues varying along a synthetic speech continuum. Thus, poor readers' difficulties with /ba/-/da/ reflected perceptual confusion between phonetically similar, though phonologically contrastive, syllables rather than difficulty in perceiving rapid spectral changes. The results are consistent with a speech-specific, not a general auditory, deficit.

Child↗
PubMed1999

Functional neuroimaging of speech perception in six normal and two aphasic subjects.

This positron emission tomography study used a correlational design to investigate neural activity during speech perception in six normal subjects and two aphasic patients. The normal subjects listened either to speech or to signal-correlated noise equivalents; the latter were nonspeech stimuli, similar to speech in complexity but not perceived as speechlike. Regions common to the auditory processing of both types of stimuli were dissociated from those specific to spoken words. Increasing rates of presentation of both speech and nonspeech correlated with cerebral activity in bilateral transverse gyri and adjacent superior temporal cortex. Correlations specific to speech stimuli were located more anteriorly in both superior temporal sulci. The only asymmetry in normal subjects was a left lateralized response to speech in the posterior superior temporal sulcus, corresponding closely to structural asymmetry on the subjects' magnetic resonance images. Two patients, who had left temporal infarction but performed well on single word comprehension tasks, were also scanned while listening to speech. These cases showed right superior temporal activity correlating with increasing rates of hearing speech, but no significant left temporal activation. These findings together suggest that the dorsolateral temporal cortex of both hemispheres can be involved in prelexical processing of speech.

Adult↗
PubMed1996

Memory effects to be considered in the design of measurements of the influence of context on speech perception.

One of the experimental parameters needed for the design of testing procedures for measuring context utilization in speech perception is the magnitude of memory effects. Such memory effects were studied using data obtained from normal-hearing subjects in experiments during which test words were presented under noise either in isolation or in the context of sentences. Each test word was presented twice; during each presentation the subject heard the test word several (five or six) different times, under progressively higher signal-to-noise (S/N) ratios. When the second presentation of a test word occurred during the same 1 h session as the first presentation, the observed memory effect was very large, being equivalent to a shift in S/N ratio of the order of 5 dB. In experiments during which the second presentation of a test word occurred after an interval of several days following the first presentation, the observed memory effect was equivalent to a shift in S/N ratio of the order of 1 dB.

Humans↗
PubMed2004

Mandarin speech perception by ear and eye follows a universal principle.

In this study, the nature of speech perception of native Mandarin Chinese was compared with that of American English speakers, using synthetic visual and auditory continua (from /ba/ to /da/) in an expanded factorial design. In Experiment 1, speakers identified synthetic unimodal and bimodal speech syllables as either /ba/ or /da/. In Experiment 2, Mandarin speakers were given nine possible response alternatives. Syllable identification was influenced by both visual and auditory sources of information for both Mandarin and English speakers. Performance was better described by the fuzzy logical model of perception than by an auditory dominance model or a weighted-averaging model. Overall, the results are consistent with the idea that although there may be differences in information (which reflect differences in phonemic repertoires, phonetic realizations of the syllables, and the phonotactic constraints of languages), the underlying nature of audiovisual speech processing is similar across languages.

Adolescent↗
PubMed2001

Disorder in sequential speech perception: a case study on pure word deafness.

We described disorders of a patient which were uniquely restricted to speech perception of syllable sequences after brain damage. The results of series of experiments using syllable sequences showed "negative recency effect," in which the subject's repetition performance at the latter syllable position was remarkably poor. Experimental analyses suggested that the "negative recency effect" could be due to dual factors: the lower rate of processing of speech sounds and the memory load of holding processes of preceding syllables imposed on the succeeding phonological processing. The results also suggested that the holding processes which imposed the memory load on the succeeding auditory phonological coding processing were modality nonspecific.

Adult↗
PubMed1992

The effects of limiting the number of Nucleus 22 cochlear implant electrodes programmed on speech perception.

The purpose of this double-blind study was to evaluate systematically the effects of varying programmed electrodes on speech perception. The performance of five subjects implanted with the Nucleus 22-electrode cochlear implant was compared on the Four-Choice Spondee test, the Central Institute for the Deaf Sentence test, and Speech Tracking across the following conditions: (1) five most apical electrodes eliminated from the subject's MAP (stimulus parameters); (2) five most basal electrodes eliminated from subject's MAP; (3) the middle five electrodes eliminated from subject's MAP; and (4) subject's current MAP. Statistically significant differences were found for the Four-Choice Spondee test and both the auditory-only and auditory-plus-lipreading Speech Tracking measures. Three subjects demonstrated poorer performance on all test measures when the five electrodes from the apical portion of the array were not programmed. Two subjects performed equally well, regardless of MAP condition. Group means for all test measures present a trend of consistently poorer performance when the -5 Apex MAPs were utilized. A subjective rating scale was consistent with the perceptual tests, with all subjects best liking their current MAP and least liking the -5 Apex MAP. Results suggest that for some subjects, a fixed place code may control their ability to use spectral information for speech discrimination. For these subjects, first formant information (F1) traditionally coded on the most apical electrodes could not be utilized as effectively when coded on the adjacent middle electrodes.

Acoustic Stimulation↗
PubMed1999

Speech perception in perceivers with hearing loss: synergy of multiple modalities.

Although we would expect that the role of visible speech in multimodal speech perception would have the greatest relevance to individuals with hearing impairment, relatively few analytic studies have been done with these participants. Their adequate understanding of spoken language usually requires information from several modalities or other sources of information. The framework of the fuzzy logical model of perception (FLMP) is used to assess how individuals with hearing impairment evaluate and integrate multiple sources of information. Given this framework, a distinction can be made between information and information processing. Within this framework, we can ask what information differences and information-processing differences exist among individuals with normal hearing and those with hearing impairment. Four experimental studies from the literature are analyzed to address these questions. Test items are presented under both unimodal and bimodal conditions. Of central interest is the nature of the bimodal performance as a function of the unimodal performance. The findings show that, although information differences obviously exist across different populations, their information processing involved in pattern recognition appears to be the same and is well described by the FLMP.

Adolescent↗
PubMed1995

Left and right hemifield advantages of fusions and combinations in audiovisual speech perception.

If a place-of-articulation contrast is created between the auditory and the visual component syllables of videotaped speech, frequently the syllable that listeners report they have heard differs phonetically from the auditory component. These "McGurk effects", as they have come to be called, show that speech perception may involve some kind of intermodal process. There are two classes of these phenomena: fusions and combinations. Perception of the syllable /da/ when auditory /ba/ and visual /ga/ are presented provides a clear example of the former, and perception of the string /bga/ after presentation of auditory /ga/ and visual /ba/ an unambiguous instance of the latter. Besides perceptual fusions and combinations, hearing visually presented component syllables also shows an influence of vision on audition. It is argued that these "visual" responses arise from basically the same underlying processes that yield fusions and combinations, respectively. In the present study, the visual component of audiovisually incongruous CV-syllables was presented in the left and the right visual hemifield, respectively. Audiovisual fusion responses showed a left hemifield advantage, and audiovisual combination responses a right hemifield advantage. This finding suggests that the process of audiovisual integration differs between audiovisual fusions and combinations and, furthermore, that the two cerebral hemispheres contribute differentially to the two classes of response.

Adult↗
PubMedDate not supplied

Speech perception of children with cochlear implants and children with traditional hearing aids.

The aim of the study was to analyse speech perception of children with cochlear implants (N = 29) and children fitted with traditional hearing aids (N = 20). One- and two-syllable words were presented auditorily in a forced choice minimal-pair discrimination task. The children repeated the word and pointed to the appropriate picture presented on computer screen. The words were minimal pairs with respect to voicing or place of articulation in stops and fricatives; among affricates the minimal pairs included the most frequently substituted fricatives and stops in addition to voicing and place of articulation. Vowel discrimination was tested in minimal pairs and in nonsense words differing only in the vowel. Unaided, all children were profoundly hearing impaired and were included in auditory-oral therapy (Verbotonal method). The smallest differences between the groups were found for stops and vowels, and the largest for fricatives and affricates. The implanted children were significantly more successful.

Adolescent↗
PubMed2004

Mandarin speech perception in nucleus CI 24 implantees using MAPs based on neural response telemetry.

The purpose of this study is to compare speech perception performance in Mandarin-speaking Nucleus CI24 implantee using standard behavior MAPs and NRT-based MAPs. Eight Nucleus CI24 users (5 years and older) participated in the study. They all fulfilled the following criteria: (1) behavioral MAP and NRT thresholds can be reliably obtained; (2) had more than 18 functioning electrodes; (3) had at least 6 months experience using CI. All subjects received speech evaluation under three different MAPs: a traditional behavioral MAP, a MAP predicted from the NRT thresholds of the E22 (electrode 22), E19, E15, E11, E8, E5, E1 and a combined MAP based on the information of NRT thresholds and behavioral threshold/comfortable levels of the E11. The speech evaluation package included word recognition test in quiet, in noise, and a Mandarin sentence test in quiet. Results showed that three MAPs are similar in some subjects, but different in other subjects. Compared to the NRT MAPs, the combined MAPs are more similar to the behavioral MAPs. There was no significant difference in the mean score of the word recognition test in quiet, in noise and sentence test under these three MAP conditions. In conclusion, although the behavioral MAPs and the NRT-based MAPs are not identical, the speech performance of Mandarin-speaking CI24 implantee using MAPs predicted from NRT thresholds appeared to be no worse than the traditional behavioral MAPs. Therefore, in certain cases that behavioral MAPs are difficult to obtain (such as in very young or multiple handicapped children), NRT-based MAPs may serve reliably as an initial estimation.

Action Potentials↗
PubMed1980

Speech-production measures of speech perception: rapid shadowing of VCV syllables.

Five listeners rapidly repeated ("shadowed") a random presentation of the vowel-consonant vowels (VCV's)/aba, apa, ama, aka, aga/. Initial vowel duration was varied to eliminate it as a temporal cue to the occurrence of the consonant. These shadowing, choice reaction times (RT's) were compared to simple RT's obtained when listeners always produced /aba/ or /ba/ to the same syllables. Both /aba/ and shadowing reactions were extremely fast (170 to 240 ms). Latency differences between the two tasks were attributable to differences in the point at which cues sufficient for responding were present. These results suggest that speech-perception decisions in shadowing are directly available to, and are perhaps made to occur at a point comparable to the consonantal release seen for the simple /aba/ responses. This result suggests that the motor organization required for a /ba/ response includes an implicit time interval appropriate for a consonantal closure.

Female↗
PubMed2003

Language perception activates the hand motor cortex: implications for motor theories of speech perception.

The precise mechanisms of how speech may have developed are still unknown to a large extent. Gestures have proven a powerful concept for explaining how planning and analysing of motor acts could have evolved into verbal communication. According to this concept, development of an action-perception network allowed for coding and decoding of communicative gestures. These were manual or manual/articulatory in the beginning and then became increasingly elaborate in the articulatory mode. The theory predicts that listening to the 'gestures' that compose spoken language should activate an extended articulatory and manual action-perception network. To examine this hypothesis, we assessed the effects of language on cortical excitability of the hand muscle representation by transcranial magnetic stimulation. We found the hand motor system to be activated by linguistic tasks, most notably pure linguistic perception, but not by auditory or visuospatial processing. The amount of motor system activation was comparable in both hemispheres. Our data support the theory that language may have evolved within a general and bilateral action-perception network.

Adult↗
PubMed2004

Comparison of speech perception performance between the Nucleus 24 and Nucleus 24 Contour cochlear implant systems.

OBJECTIVE: To compare the 1-, 3-, and 6-month postoperative speech perception scores obtained by a group of subjects who received the new perimodiolar array (Nucleus Contour) cochlear implant with those obtained by a group of subjects implanted with the straight electrodes of the previous-generation Nucleus 24 device. MATERIAL AND METHODS: The speech performance of 10 postlingually deafened adults implanted with the Nucleus Contour device was compared with that of matched controls who received the Nucleus 24 model. Objective measures included word and sentence speech recognition scores. RESULTS: Patients implanted with the Nucleus Contour device obtained significantly higher word and sentence recognition scores after short-term use of the implant compared to those obtained by patients implanted with the Nucleus 24 model. CONCLUSION: Further long-term studies are required to determine whether the Nucleus Contour CI recipients continue to improve over time.

Adolescent↗
PubMed2001

Speech perception and functional benefit after multichannel cochlear implantation.

This study was done to investigate the effect of a multichannel cochlear implant on speech perception and the functional benefit of cochlear implantation in Finnish-speaking postlingually deafened adults. Fourteen subjects were enrolled. Sentence and word recognition were studied with open-set tests auditorily only. One year after implantation, the listening performance was assessed by case histories and interviews. Before implantation for subjects with a hearing aid, the mean recognition score was 38% for sentences and 17% for words. One year after switching on the implant, the mean recognition score was 84% for sentences and 70% for words. Before implantation, the majority of the subjects were not aware of environmental sounds and only a few were able to recognize some environmental sounds. One year after switching on the implant, the majority of the subjects were able to use the telephone with a familiar speaker. All the subjects were able to recognize speech auditorily only and had thus gained good functional benefit from the implant.

Acoustic Stimulation↗
PubMed1989

Influence of sentence context on speech perception in young and older adults.

This study investigated the ability of young and older adults to use contextual cues to understand speech in ordinary listening situations. Key word recognition scores were obtained with the Speech Perception in Noise (SPIN) test. Sentence lists contained 50 key words preceded by a high predictability (HP), low predictability (LP), or a carrier phrase (CP) context accompanied by a varying background of multitalker babble. Comparison of the low context items vs the number of meaningfully rich items correctly identified provided an index of the listener's ability to use contextual information in the HP sentences. The LP and CP score reflected the individual's ability to recognize items based only on the acoustic-phonetic information of the key words. Most individuals were able to take some advantage of contextual cues in everyday sentences; however, the older listeners were more adversely affected by background noise than younger listeners. For clinical utilization of the SPIN test, further research is needed to develop normative data as a function of age to make it an "age-fair" test.

Adult↗
PubMed1993

[Speech perception in children fitted with Nucleus mini system 22 implants].

Currently there are over 380 european children implanted with the Nucleus device. A battery of speech perception tests has been adapted and translated into German, French and English by Cochlear AG to evaluate the benefits of the cochlear implant for european children. The tests evaluate a hierarchy of auditory skills classified into four levels including: detection of speech sounds, speech pattern identification; speech identification and speech recognition. A child's auditory-visual skills are also assessed. Over 100 children randomly selected from participating clinics have been assessed postoperatively with these measures and the results analyzed. These children are representative of the diversity amongst the european child population in terms of etiology of deafness, onset of deafness, duration of deafness and experience with the implant. All children were able to score significantly above chance for the first two perceptual tests. Test results for this group of children suggest that children with a later onset and shorter duration of deafness tend to perform better on some auditory tasks than children deafened earlier in life and for a longer period of time. Furthermore it appears that the children's performance on these tests improves with increasing implant experience.

Age Factors↗