ISSN:0196-0202    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectiveThe scientific study of the perception of spoken language has been an exciting, prolific, and productive area of research for more than 50 yr. We have learned much about infants’ and adults’ remarkable capacities for perceiving and understanding the sounds of their language, as evidenced by our increasingly sophisticated theories of acquisition, process, and representation. We present a selective, but we hope, representative review of the past half century of research on speech perception, paying particular attention to the historical and theoretical contexts within which this research was conducted. Our foci in this review fall on three principle topics: early work on the discrimination and categorization of speech sounds, more recent efforts to understand the processes and representations that subserve spoken word recognition, and research on how infants acquire the capacity to perceive their native language. Our intent is to provide the reader a sense of the progress our field has experienced over the last half century in understanding the human’s extraordinary capacity for the perception of spoken language.

ISSN:0196-0202    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectiveThe purpose of this study was to separate the composite components of the auditory 40 Hz steady-state potentials (40 Hz SSP), by differentially augmenting them with filtering at different low passes, and to compare them with their counterparts in the transient-evoked auditory middle-latency evoked potentials (AMEP).MethodsTransient-evoked AMEP to 3.3/sec clicks and 40 Hz SSP to 40/sec clicks were recorded from 18 subjects using three orthogonally positioned electrode pairs. Each type of potentials was filtered with a 100 Hz and with a 50 Hz low pass. Equivalent dipoles of components were estimated using Three-channel Lissajous’ Trajectories and compared between filter settings (50 and 100 Hz low pass) and between the transient-evoked and the steady-state potentials.ResultsWith a band pass of 3 to 100 each period of the 40 Hz SSP consisted of a brain stem (V) and four cortical (P0, Na, Pa1, Pa2, and Nb) components. The lower-frequency components of the 40-Hz response corresponded in latency and equivalent dipole orientation to the later transient-evoked cortical AMEP components, whereas the higher-frequency components corresponded to the earlier, brain stem and primary cortical components of transient-evoked AMEP. Band-pass filtering at 3 to 50 Hz resulted in fewer components, as early brain stem and primary cortical components diminished.ConclusionsA band pass of 3 to 100 Hz for recording the 40 Hz SSP results in a composite waveform comprising of distinct brain stem and cortical generators with different orientations of their equivalent dipoles. The relative contributions of the multiple constituents are affected by the acquisition filter low pass: brain stem and primary cortical generators mostly contribute the high frequencies and later cortical contributions dominate the lower frequencies.

ISSN:0196-0202    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

The recent report by Peter Dallos and colleagues of the gene and protein responsible for outer hair cell somatic motility(Zheng, Shen, He, Long, Madison, & Dallos, 2000), and the work of James Hudspeth and colleagues demonstrating that vestibular stereocilia are capable of providing power that may boost the vibration of structures within the inner ear(Martin & Hudspeth, 1999), presents the tantalizing possibility that we may not be far away from answering the question what drives mechanical amplification in the mammalian cochlea? This article reviews the evidence for and against each of somatic motility as the motor, and a motor in the hair cell bundle, producing cochlear mechanical amplification. We consider three models based on somatic motility as the motor and two based on a motor in the hair cell bundle. Available evidence supports a hair cell bundle motor in nonmammals but the upper frequency limit of mammalian hearing in general exceeds that of nonmammals, in many cases by an order of magnitude or more. Only time will tell whether an evolutionary dichotomy exists(Manley, Kirk, Köppl, & Yates, 2001).

ISSN:0196-0202    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

ObjectiveWhen a syllable such as “sea” or “she” is spoken, listeners with normal hearing extract evidence of the fricative consonant from both the fricative noise and the following vocalic segment. If the fricative noise is made ambiguous, listeners may still perceive “s” or “sh” categorically, depending on information in the vocalic segment. Do children whose auditory experience comes from electrical stimulation also display this effect, in which a subsequent segment of speech disambiguates an earlier segment?DesignUnambiguous vowels were appended to ambiguous fricative noises to form tokens of the words “she,” “sea,” “shoe,” and “Sue.” A four-choice identification test was undertaken by children with normal hearing (N= 29), prelingually deaf children with the Nucleus Spectra-22 implant system using the SPEAK coding strategy (N= 13), postlingually deafened adults with the same implant system (N= 26), and adults with normal hearing (N= 10). The last group undertook the test before and after the stimuli were processed to simulate the transformations introduced by the SPEAK coding strategy.ResultsAll four groups made use of vocalic information. Simulated processing reduced the use made by normal-hearing adults. Implanted subjects made less use than the other groups, with no significant difference between implanted children and implanted adults. The highest levels of use by implanted subjects were within one standard deviation of the mean level displayed when normal-hearing adults listened to processed stimuli. Analyses showed that the SPEAK strategy distorted formant contours in the vocalic segments of the stimuli in ways that are compatible with the errors of identification made by implanted subjects.ConclusionsSome children with implants can extract information from a following vowel to disambiguate a preceding fricative noise. The upper limit on this ability may be set by distortions introduced by the implant processor, rather than by the auditory experience of the child.

ISSN:0196-0202    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:2002

数据来源: OVID