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PubMed2001

Evaluation of the Computer-assisted Speech Perception Assessment Test (CASPA).

Interlist equivalency and short-term practice effects were evaluated for the recorded stimuli of the Computer-Assisted Speech Perception Assessment (CASPA) Test. Twenty lists, each consisting of 10 consonant-vowel-consonant words, were administered to 20 adults with normal hearing. The lists were presented at 50 dB SPL (Leq) in the presence of spectrally matched steady-state noise (55 dB SPL Leq). Phoneme recognition scores for the first list presented were significantly lower than for the second through the twentieth list presented, indicating a small practice effect. Phoneme scores for 4 of the lists (3, 6, 7, and 16) were significantly higher than scores for the remaining 16 lists by approximately 10 percentage points. Eliminating the effects of interlist differences reduced the 95 percent confidence interval of a test score based on a single list from 18.4 to 16.1 percentage points. Although interlist differences have only a small effect on confidence limits, some clinicians may wish to eliminate them by excluding lists 3, 6, 7, and 16 from the test. The practice effect observed here can be eliminated by administering one 10-word practice list before beginning the test.

Adult↗

PubMed2003

Brain activity during audiovisual speech perception: an fMRI study of the McGurk effect.

fMRI was used to assess the relationship between brain activation and the degree of audiovisual integration of speech information during a phoneme categorization task. Twelve subjects heard a speaker say the syllable /aba/ paired either with video of the speaker saying the same consonant or a different one (/ava/). In order to manipulate the degree of audiovisual integration, the audio was either synchronous or +/- 400 ms out of phase with the visual stimulus. Subjects reported whether they heard the consonant /b/ or another consonant; fewer /b/ responses when the audio and visual stimuli were mismatched indicated higher levels of visual influence on speech perception (McGurk effect). Active brain regions during presentation of the incongruent stimuli included the superior temporal and inferior frontal gyrus, as well as extrastriate, premotor and posterior parietal cortex. A regression analysis related the strength of the McGurk effect to levels of brain activation. Paradoxically, higher numbers of /b/ responses were positively correlated with activation in the left occipito-temporal junction, an area often associated with processing visual motion. This activation suggests that auditory information modulates visual processing to affect perception.

Acoustic Stimulation↗

PubMed1999

Comparison of speech perception in pediatric CLARION cochlear implant and hearing aid users.

Multichannel cochlear implants (CIs) allow many profoundly deaf children to achieve high levels of speech perception. In order to develop optimal criteria for implantation, it is crucial to test representative samples (or, if possible, full populations) of CI users and compare their results to those of hearing aid (HA) users of the same age and communication mode (oral or total communication) to determine which subgroups of HA users may obtain more perceptual benefit from a CI than from an HA. Word and phoneme identification skills of deaf children who use either HAs or CIs were evaluated and compared. The CI group included all of the prelingually deaf children in the United States who were implanted with the CLARION Multi-Strategy Cochlear Implant during the clinical trial (as of January 1998). Before implantation, the mean scores on the PB-K test (scored phonemically) were lower for prospective CI users than for HA users. However, by 12 to 18 months postimplantation, the average scores for the CI users were higher than those of HA users with residual hearing in the 101- to 110-dB hearing level (HL) range. The CI scores were similar to those of HA users with residual hearing in the 90- to 100-dB HL range.

Adolescent↗

PubMed1996

Speech perception is hearing sounds, not tongues.

Three types of evidence are reviewed which cast doubt on claims that recovery of the speaker's articulations is an inherent part of speech perception: (a) Phonological data (e.g., universal tendencies of languages' segment inventories, phonotactic patterns, sound changes, etc.) show unmistakably that the acoustic-auditory properties of speech sounds, not their articulations, are the primary determinant of their behavior. (b) Infants and various nonhuman species can differentiate certain sound contrasts in human speech even though it is highly unlikely that they can deduce the vocal tract movements generating the sounds. (c) Humans can differentiate many nonspeech sounds almost as complex as speech, e.g., music, machine noises, as well as bird and monkey vocalizations, where there is little or no possibility of recovering the mechanisms producing the sounds.

Humans↗

PubMed2006

Audibility and speech perception of children using wide dynamic range compression hearing AIDS.

PURPOSE: This study examined the relation of audibility for frequency-specific sounds and the Speech Intelligibility Index (SII) to speech perception abilities of children with sensorineural hearing loss using digital signal-processing hearing aids with wide dynamic range compression. METHOD: Twenty-six children age 5-15 years with pure-tone averages (0.5, 1.0, and 2.0 kHz) from 60-98 dB HL participated. Three subgroups were created based on the compression characteristics of each hearing aid. Minimum audibility was determined using aided thresholds for frequency-modulated tones and the SII calculated at 55 and 70 dB SPL using the simulated real-ear output of the hearing aid. The Lexical Neighborhood Test (LNT; K. I. Kirk, D. B. Pisoni, & M. J. Osberger, 1995) was presented at 50 and 70 dB SPL. RESULTS: LNT scores at 70 dB SPL were significantly higher than at 50 dB SPL. Average aided thresholds at 0.5, 1.0, and 2.0 kHz were negatively correlated with LNT scores at 50 dB SPL, and SIIs at 55 and 70 dB SPL were positively correlated with LNT scores at 50 and 70 dB SPL. CONCLUSIONS: Results support using aided thresholds and speech test scores at soft to loud levels as part of the amplification fitting process.

Auditory Threshold↗

PubMed2002

Features of stimulation affecting tonal-speech perception: implications for cochlear prostheses.

Tone languages differ from English in that the pitch pattern of a single-syllable word conveys lexical meaning. In the present study, dependence of tonal-speech perception on features of the stimulation was examined using an acoustic simulation of a CIS-type speech-processing strategy for cochlear prostheses. Contributions of spectral features of the speech signals were assessed by varying the number of filter bands, while contributions of temporal envelope features were assessed by varying the low-pass cutoff frequency used for extracting the amplitude envelopes. Ten normal-hearing native Mandarin Chinese speakers were tested. When the low-pass cutoff frequency was fixed at 512 Hz, consonant, vowel, and sentence recognition improved as a function of the number of channels and reached plateau at 4 to 6 channels. Subjective judgments of sound quality continued to improve as the number of channels increased to 12, the highest number tested. Tone recognition, i.e., recognition of the four Mandarin tone patterns, depended on both the number of channels and the low-pass cutoff frequency. The trade-off between the temporal and spectral cues for tone recognition indicates that temporal cues can compensate for diminished spectral cues for tone recognition and vice versa. An additional tone recognition experiment using syllables of equal duration showed a marked decrease in performance, indicating that duration cues contribute to tone recognition. A third experiment showed that recognition of processed FM patterns that mimic Mandarin tone patterns was poor when temporal envelope and duration cues were removed.

Acoustic Stimulation↗

PubMed1986

Lesion locations associated with speech perception deficits following penetrating head injury.

Speech discrimination and identification tasks assessing voicing and place distinctions were given to 16 unilaterally brain injured subjects free of aphasic or dysarthric symptoms 12-15 yr post head injury. Seven subjects did not demonstrate any difficulty with these speech tasks, while five left- and four right-brain-injured subjects showed moderate difficulties. These difficulties were more pronounced on the discrimination than on the identification tasks. Analysis of CT scans demonstrated that the lesion locations most clearly associated with the speech discrimination deficits were upper levels of the white matter subjacent to cortical regions in either hemisphere.

Brain↗

PubMed1997

Neurobiology of speech perception.

The mechanisms by which human speech is processed in the brain are reviewed from both behavioral and neurobiological perspectives. Special consideration is given to the separation of speech processing as a complex acoustic-processing task versus a linguistic task. Relevant animal research is reviewed, insofar as these data provide insight into the neurobiological basis of complex acoustic processing in the brain.

Brain↗

PubMed2001

Speech perception and functional benefit after cochlear implantation: a multicentre survey in Finland.

This study was done to survey the effect of cochlear implantation on hearing level, speech perception and listening performance in Finnish-speaking adults. The subjects of the study comprise 67 adults. Pure-tone thresholds (0.125-8 kHz), word recognition and listening performance were studied before and after implantation. After switch-on of the implant, the median values of PTA(0.5-4 kHz) in the sound field were fairly stable across the evaluation period. Three months after switch-on of the implant, the mean word recognition score was 54%. There was clear improvement in the mean word recognition scores over a longer period of time, the mean score being 71% 24 months after switch-on. Six months after switch-on, the majority of subjects (40/48) were able to recognize some speech without speechreading, and 26 of these 48 subjects were able to use the telephone with a known speaker, gaining good functional benefit from the implantation.

Adult↗

PubMed1990

Speech perception in low-pass filtered noise for normal and hearing-impaired listeners.

Two experiments were conducted concerning speech perception in noise. In Experiment 1, a comparison was made between adaptive and fixed-level procedures to estimate the S/N ratio at which 50% correct performance occurred for nonsense syllables for normal-hearing listeners. The two methods yield similar S/N ratio estimates, but the consonant confusions found with the fixed-level method could not be predicted accurately from the adaptive procedure. In Experiment 2, the adaptive procedure was used to estimate the S/N ratio for a 50% performance level in low-pass filtered noise with a range of cutoff frequencies. Data were obtained from 5 normal-hearing listeners at two speech levels (50 and 75 dB SPL) and 4 hearing-impaired listeners at one speech level (75 dB SPL). The hearing-impaired listeners required a better S/N ratio than the normal listeners at either presentation level for all except the widest bandwidth, where their S/N ratios began to converge with the normal values. In addition, the S/N ratios for the hearing-impaired listeners plateaued at relatively narrow bandwidths (0.75 to 2.5 kHz) compared to the normal-hearing group (3.0 to 5.0 kHz). That is, the addition of high-frequency components to the noise did not alter performance. These findings suggest that the hearing-impaired listeners may have relied upon either low-frequency cues or prosodic cues in the perception of these test items.

Adaptation, Physiological↗

PubMedDate not supplied

The reflex theory of speech perception.

The perceptual confusions among Chinese consonants are analyzed and a comparative study is made for several languages, and then a reflex theory is presented. The results show that: (i) the distinctive features of speech are important perceptual cues, of which the manner of articulation is the more important one, (ii) the feature systems are different for different languages, (iii) the social characteristics of language i.e., linguistic constructions, strongly influence speech perception which is of a unitary process based on the physical characteristics in combination with the social characteristics of speech. The principal features of Chinese consonants and its capability to transmit information are given. It is shown that the construction of Chinese syllables is good for the syllable articulation.

Humans↗

PubMed2003

Human ECoG analysis during speech perception using matching pursuit: a comparison between stochastic and dyadic dictionaries.

We use the matching pursuit (MP) algorithm to detect induced gamma activity in human EEG during speech perception. We show that the MP algorithm is particularly useful for detecting small power changes at high gamma frequencies (> 70 Hz). We also compare the performance of the MP using a stochastic versus a dyadic dictionary and show that despite the frequency bias the time-frequency power plot (averaged over 100 trials) generated by the dyadic MP is almost identical (> 98.5%) to the one generated by the stochastic MP. However, the dyadic MP is computationally much faster than the stochastic MP.

Algorithms↗

PubMed2006

Temporal window of integration in auditory-visual speech perception.

Forty-three normal hearing participants were tested in two experiments, which focused on temporal coincidence in auditory visual (AV) speech perception. In these experiments, audio recordings of/pa/and/ba/were dubbed onto video recordings of /ba/or/ga/, respectively (ApVk, AbVg), to produce the illusory "fusion" percepts /ta/, or /da/ [McGurk, H., & McDonald, J. (1976). Hearing lips and seeing voices. Nature, 264, 746-747]. In Experiment 1, an identification task using McGurk pairs with asynchronies ranging from -467 ms (auditory lead) to +467 ms was conducted. Fusion responses were prevalent over temporal asynchronies from -30 ms to +170 ms and more robust for audio lags. In Experiment 2, simultaneity judgments for incongruent and congruent audiovisual tokens (AdVd, AtVt) were collected. McGurk pairs were more readily judged as asynchronous than congruent pairs. Characteristics of the temporal window over which simultaneity and fusion responses were maximal were quite similar, suggesting the existence of a 200 ms duration asymmetric bimodal temporal integration window.

Acoustic Stimulation↗

PubMed1999

The role of phonological awareness, speech perception, and auditory temporal processing for dyslexia.

There is strong evidence that auditory processing plays a major role in the etiology of dyslexia. Auditory temporal processing of non-speech stimuli, speech perception, and phonological awareness have been shown to be influential in reading and spelling development. However, the relationship between these variables remains unclear. In order to analyze the influence of these three auditory processing levels on spelling, 19 dyslexic and 15 control children were examined. Significant group differences were found for all speech variables, but not for any non-speech variable. Structural equation modeling resulted in a fairly simple model with direct paths to the respective next lower level. One additional path from preattentive speech processing to spelling had to be included in order to improve the model fit. These results strengthen the role of speech and phonological processing for the etiology in dyslexia.

Attention↗

PubMedDate not supplied

Mismatch negativity and late discriminative negativity in investigating speech perception and learning in children and infants.

For decades, behavioral methods, such as the head-turning or sucking paradigms, have been the primary tools to investigate speech perception and learning of a language in infancy. Recently, however, new methods provided by event-related potentials have emerged. These are called mismatch negativity (MMN) and late discriminative negativity (LDN). MMN, the brain's automatic change-detection response in audition, has been intensively used in adults in both basic and clinical studies for longer than 20 years. LDN, on the other hand, was only recently discovered. There seem to be many differences between these two responses. MMN is developmentally quite stable and can be obtained even from preterm infants. LDN, however, can be obtained most reliably from young children, and its amplitude decreases as a function of age. New data suggest that both of these responses have a special role in language processing, although both of them can also be elicited by nonspeech stimuli.

Child↗

PubMed2005

Speech perception as a window for understanding plasticity and commitment in language systems of the brain.

In this article, we provide a critical review of the literature on speech perception and phonological processing in infancy, and in populations with different experiential histories as a window to understanding how the notion of critical periods might apply to the acquisition of one part of language: the sound system. We begin by suggesting the use of the term "optimal period" because (a) both the onset (opening) and offset (closing) of openness to experience is variable rather than absolute and (b) phonological acquisition involves the emergence of a series of nested capabilities, each with its own sensitive period and each best explained at one of several different levels of specificity. In support, we cite evidence suggesting that to fully understand plasticity and commitment in phonological acquisition, it is necessary to consider not only the biological and experiential factors which may contribute to the onset and the offset of openness to experience but also how the sequentially developing parts of phonology constrain and direct development. In summary, we propose a nested, cascading model wherein biology, experience, and functional use each contribute.

Brain↗

PubMed1990

Visual biasing of normal and impaired auditory speech perception.

Intersensory biasing occurs when cues in one sensory modality influence the perception of discrepant cues in another modality. Visual biasing of auditory stop consonant perception was examined in two related experiments in an attempt to clarify the role of hearing impairment on susceptibility to visual biasing of auditory speech perception. Fourteen computer-generated acoustic approximations of consonant-vowel syllables forming a /ba-da-ga/ continuum were presented for labeling as one of the three exemplars, via audition alone and in synchrony with natural visual articulations of /ba/ and of /ga/. Labeling functions were generated for each test condition showing the percentage of /ba/, /da/, and /ga/ responses to each of the 14 synthetic syllables. The subjects of the first experiment were 15 normal-hearing and 15 hearing-impaired observers. The hearing-impaired subjects demonstrated a greater susceptibility to biasing from visual cues than did the normal-hearing subjects. In the second experiment, the auditory stimuli were presented in a low-level background noise to 15 normal-hearing observers. A comparison of their labeling responses with those from the first experiment suggested that hearing-impaired persons may develop a propensity to rely on visual cues as a result of long-term hearing impairment. The results are discussed in terms of theories of intersensory bias.

Adult↗

PubMed1991

Assessment of speech perception in children with cochlear implants and tactile aids: what should the future hold?

The purpose of this paper is to propose a rationale for the future development of speech perception evaluation materials for children using either cochlear implants or vibrotactile aids as sensory prosthetic devices. It is suggested that future evaluation tools extend beyond the assessment of device efficacy. In particular, they should address issues of normal perceptual development in children, as well as the results of intervention with children using these sensory prosthetic devices.

Child↗