摘要:

Objective:A fundamental problem in the study of human spoken word recognition concerns the structural relations among the sound patterns of words in memory and the effects these relations have on spoken word recognition. In the present investigation, computational and experimental methods were employed to address a number of fundamental issues related to the representation and structural organization of spoken words in the mental lexicon and to lay the groundwork for a model of spoken word recognition.Design:Using a computerized lexicon consisting of transcriptions of 20,000 words, similarity neighborhoods for each of the transcriptions were computed. Among the variables of interest in the computation of the similarity neighborhoods were: 1) the number of words occurring in a neighborhood, 2) the degree of phonetic similarity among the words, and 3) the frequencies of occurrence of the words in the language. The effects of these variables on auditory word recognition were examined in a series of behavioral experiments employing three experimental paradigms: perceptual identification of words in noise, auditory lexical decision, and auditory word naming.Results:The results of each of these experiments demonstrated that the number and nature of words in a similarity neighborhood affect the speed and accuracy of word recognition. A neighborhood probability rule was developed that adequately predicted identification performance. This rule, based onLuce's (1959)choice rule, combines stimulus word intelligibility, neighborhood confusability, and frequency into a single expression. Based on this rule, a model of auditory word recognition, the neighborhood activation model, was proposed. This model describes the effects of similarity neighborhood structure on the process of discriminating among the acoustic-phonetic representations of words in memory. The results of these experiments have important implications for current conceptions of auditory word recognition in normal and hearing impaired populations of children and adults.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:To identify patients with primary auditory neuropathies whose cochlear potentials to a 100 µsec click persist after click cessation and simulate synchronous auditory brain stem responses (ABRs) at high intensities.Design:ABRs to condensation and rarefaction clicks, as well as Maximum Length Sequence ABRs and one transtympanic electrocochleogram (ECochG), were collected from five infants with absent middle ear muscle reflexes and normal or near normal otoacoustic emissions. These infants failed ALGO screens, which used alternating polarity clicks, and/or failed full ABRs done elsewhere with alternating polarity clicks.Results:When ABRs were collected in response to a single polarity pulse, they revealed robust and reproducible wave forms over 4 to 6 msec that initially were mistaken for a normal ABR by the referring agents. However, when condensation and rarefaction click data are compared, the waveforms change polarity when the stimulus is inverted. Furthermore, the waveforms fail to shift in latency as the intensity of the stimulation is reduced. Transtympanic ECochG on one of the children revealed the same polarity reversal and fixed latency functions, confirming that they were cochlear rather than neural responses.Conclusions:Comparing responses with positive versus negative polarity clicks may help separate ABRs from cochlear potentials and alert clinicians to the possibility of an auditory neuropathy. Therefore, absent or abnormal ABRs in the presence of normal otoacoustic emissions need not always implicate a purely "central disorder," but might be consistent with dysfunction between outer hair cells and primary afferent fibers.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:1) To examine the distribution of behavioral hearing thresholds in a group of children who had shown no click-evoked auditory brain stem response (ABR) at maximum presentation levels. 2) To describe the relationship between the 90 Hz steady-state evoked potential (SSEP) and behavioral thresholds in these subjects.Design:A retrospective study based on clinical findings obtained from 108 infants and young children. Each of these children had shown no recordable ABR to clicks presented at maximum levels (100 dB nHL). SSEP audiograms were obtained using AM/FM tones at the octave frequencies 250 to 4000 Hz. The results of these evoked potential assessments were compared with hearing thresholds established behaviorally.Results:Click-ABR assessment could not differentiate between the subjects in our sample with total hearing losses and those with useful residual hearing. Although some of the ears were anacusic, more than a quarter showed residual hearing at each of the audiometric frequencies. Furthermore, at least 10% of the behavioral thresholds at each frequency fell within the moderate/severe hearing loss range. A far closer relationship was observed between SSEP and hearing thresholds. On occasions where the SSEP was absent at maximum levels, 99.5% of the ears showed either a total loss or a behavioral threshold within 10 dB of that level. When an SSEP was obtained, the hearing threshold was typically within 5 dB of the SSEP threshold.Conclusion:The results suggested that in our group of selected subjects, the SSEP technique was able to assess ears with only minimal amounts of residual hearing. Where the brevity of the acoustic click limits both its frequency specificity and its presentation level, the modulated tones used for SSEP testing allow accurate, frequency-specific assessment at high presentation levels.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:We tested the hypothesis that the use of nonoccluding earmolds for hearing aid fittings could optimize auditory localization in the vertical plane for people with moderate, low-frequency hearing losses and good hearing at frequencies above 4000 Hz. This benefit was expected to arise from leaving the pinna unobstructed and by optimizing hearing (unaided) for frequencies above the hearing aid's limit.Design:Twenty-two participants had hearing losses greater than 30 dB over the range 250 to 2000 Hz and had minimal losses (<30 dB) at 6000 Hz and 8000 Hz. Their auditory localization was tested, using a horizontal arc and a vertical arc of loud-speakers, when listening unaided and when fitted bilaterally with Behind The Ear hearing aids with three earmold types-closed(occluded), open (partly occluded), sleeve (nonoccluded).Results:Localization of vertical plane sound sources was significantly poorer for the closed earmold condition than for unaided. The open and sleeve conditions were better than the closed condition, and, for the sleeve earmold, vertical localization was almost equal to that unaided. The capacity to benefit from using open rather than closed earmolds was related to hearing level; people with the best hearing at 4000, 6000, and 8000 Hz received the most benefit. There was limited evidence that open earmolds also can be advantageous for some aspects of horizontal plane localization.Conclusions:Nonoccluding earmolds optimize aided vertical localization for hearing aid users with good high-frequency hearing. The "sleeve" earmold, so far used only in research, may be a useful clinical option.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:To examine changes over time in consonant feature production by children with profound hearing impairments who used either the Nucleus multichannel cochlear implant or the multichannel vibrotactile aid, Tactaid 7.Design:Imitative consonant productions of children with prelingual deafness were elicited and transcribed at two intervals: 1) before receiving their respective devices (predevice interval), and 2) after an average of 1.5 yr of device use (postdevice interval). The consonant productions were analyzed in terms of the percentage of consonant features (manner, place, and voicing) produced by the child that matched the features of the examiner's target. The percentage of features produced correctly was then averaged across repetitions, vowel environments, and participants within each group.Results:At the predevice interval, the cochlear implant and Tactaid 7 participants demonstrated similar imitative consonant production abilities. After an average of 1.5 yr of device use, the cochlear implant participants demonstrated significantly greater gains than did the Tactaid 7 participants for the features of voicing and place of articulation. Although the cochlear implant participants showed a trend towards better production of the consonant manner features, this difference failed to reach significance.Conclusions:The current results suggest that the use of a multichannel sensory aid yields improvements in consonant feature production. Furthermore, use of a cochlear implant appears to promote the production of consonant voicing and place features to a greater degree than does the use of a multichannel tactile aid.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID