ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTWe compared within-subjects electrical thresholds and dynamic ranges obtained with direct round-window and transtympanic promontory stimulation carried out preoperatively in 12 patients who were candidates for a cochlear implant. Square waves with frequencies of 50, 100, 200, and 400 Hz were delivered in a 50% duty cycle to both sites in each patient. With the exception of threshold at 50 Hz (promontory thresholds were lower than round-window thresholds), there were no statistically significant differences for either thresholds or dynamic ranges between the two sites of stimulation. There was a general trend for round-window thresholds to be lower and dynamic ranges larger, especially for the higher frequencies of stimulation. Mean threshold slopes for the two sites of stimulation were nearly identical.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTMagnetoencephalographic (MEG) applications in auditory evoked field (AEF) recordings have demonstrated that both tonotopicity and amplitopicity exist in the auditory cortex. The present study was conducted to determine whether previously reported characteristics of the AEF could be identified in multichannel cortical auditory evoked potential N1e (e.g., the electrical correlate of the magnetically recorded N1m) component recordings. Multichannel auditory evoked potentials from 11 young normal adults were collected after monaural tone burst stimuli of 250, 1000, and 4000 Hz. Results demonstrated that N1e amplitudes after stimulation at 250 Hz were significantly larger than those obtained after stimulation at 1000 or 4000 Hz. These frequency-specific differences existed for latency as well. Responses obtained after stimulation at 250 Hz were, on the average, 13 msec longer than those obtained after stimulation at 1000 or 4000 Hz. Also, contralateral latencies were significantly shorter than ipsilateral latencies. Although the significant frequency-specific amplitude results support the findings of previous investigators, the frequency-related latency differences have not been described. An explanation of these differences may exist in the spatial differences in the reception areas for low- and high-frequency tones in the primary auditory cortex.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTAn analysis is presented of the detectability of the two types of otoacoustic emissions being considered for use in clinical tests of hearing. It is estimated that, for equal emission levels and equal probability of error, measurement of distortion-product emissions can be made at least 30 times faster than transient-evoked emissions using current techniques.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTThe purpose of this project was to determine if the hearing-impaired population reports satisfaction with their ability to converse over the telephone in both aided and unaided situations. For this study, we surveyed 104 hearing-impaired persons using a 43 item questionnaire that investigates problems that hearing-impaired people encounter when using the telephone. The questionnaire also probes the solutions that hearing-impaired people use for overcoming these problems. Of the 91 respondents who wear hearing aids, 55% use their aids while operating the telephone. However, 70% of these respondents reported that coupling the hearing aid to the telephone is problematic. Use of a telephone amplifier was reported by 73% of the sampled population. The majority of the subjects, 75%, indicated an interest in improvements in telephone communications for hearing-impaired people.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTFifteen adults with bilaterally symmetrical mild and/or moderate sensorineural hearing loss completed a paired-comparison task designed to elicit sound quality preference judgments for monaural/binaural hearing aid processed signals. Three stimuli (speech-in-quiet, speech-in-noise, and music) were recorded separately in three listening environments (audiometric test booth, living room, and a music/lecture hall) through hearing aids placed on a Knowles Electronics Manikin for Acoustics Research. Judgments were made on eight separate sound quality dimensions (brightness, clarity, fullness, loudness, nearness, overall impression, smoothness, and spaciousness) for each of the three stimuli in three listening environments. Results revealed a distinct binaural preference for all eight sound quality dimensions independent of listening environment. Binaural preferences were strongest for overall impression, fullness, and spaciousness. Stimulus type effect was significant only for fullness and spaciousness, where binaural preferences were strongest for speech-in-quiet. After binaural preference data were obtained, subjects ranked each sound quality dimension with respect to its importance for binaural listening relative to monaural. Clarity was ranked highest in importance and brightness was ranked least important. The key to demonstration of improved binaural hearing aid sound quality may be the use of a paired-comparison format.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTThe 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.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTThis article describes an evaluation of an in the ear hearing aid, which applies fast-acting full dynamic range compression independently in two frequency bands. This can compensate for the loudness recruitment typically associated with sensorineural hearing loss. The crossover frequency between the two bands and the gain and compression ratio in each band are programmable to suit the individual patient. Twenty subjects with moderate sensorineural hearing loss were tested in a counterbalanced order using the aid programmed as a linear amplifier (condition L) and as a two-band compressor (condition C). All subjects were fitted binaurally. Subjects were also tested without hearing aids (condition U) and using the hearing aids that they normally wore (condition Own). Speech intelligibility was measured in quiet at three sound levels (50, 65, and 80 dB SPL), and speech reception thresholds (SRTs) in 12-talker babble were measured under monaurally and bin-aurally aided conditions, with the speech and babble both coincident and spatially separated. In condition C, speech intelligibility in quiet was high at all sound levels. Speech intelligibility at the two lower levels decreased in condition L, and decreased still further in conditions Own and U. Condition C gave, on average, better speech intelligibility in babble (lower SRTs) than conditions L, Own, or U. The advantage of condition C over condition L varied across subjects and was correlated with the dynamic range for tones at high frequencies; small dynamic ranges were associated with greater benefit from compression. A significant advantage for binaural aiding was found both when the speech and noise were spatially separated and when they were coincident. The binaural advantage was similar for the C and L conditions, indicating that the independent compression at the two ears did not adversely affect the use of binaural cues. Questionnaires on the subjects' experiences with the aids in everyday life indicated that they generally preferred condition C over condition L.

ISSN:0196-0202    

出版商:OVID    

年代:1992

数据来源: OVID