摘要:

Objective:To define mechanisms accounting for transient deafness in three children(two siblings, ages 3 and 6, and an unrelated child, age 15) when they become febrile.Design:Audiometric tests (pure-tone audiometry, speech and sentence comprehension), tympanometry, middle ear muscle reflex thresholds, otoacoustic emissions (OAEs), and electrophysiological methods (auditory brain stem responses [ABRs], sensory evoked potentials, peripheral nerve conduction velocities) were used to test the children when they were afebrile and febrile.Results:ABRs, when afebrile, were abnormal with a profound delay of the IV-V and absence of waves I-III. The ABR in one of the children, tested when febrile, showed no ABR components. Measures of cochlear receptor function using OAEs were normal in both febrile and afebrile states. Cochlear microphonic potentials were present in the three children, and a summating potential was likely present in two. When afebrile, there was a mild threshold elevation for all frequencies in the 15-yr-old and a mild elevation of thresholds for just low frequencies in the two siblings. Speech comprehension in quiet was normal but impaired in noise. One of the siblings tested when febrile had a profound elevation (>80 dB) of pure-tone thresholds and speech comprehension was absent. Acoustic reflexes subserving middle ear muscles and olivocochlear bundle were absent when febrile and when afebrile. No other peripheral or cranial nerve abnormalities were found in any of the children. Sensory nerve action potentials from median nerve in one of the children showed no abnormalities on warming of the hand to 39°C.Conclusion:These children have an auditory neuropathy manifested by a disorder of auditory nerve function in the presence of normal cochlear outer hair cell functions. They develop a conduction block of the auditory nerves when their core body temperature rises due, most likely, to a demyelinating disorder of the auditory nerve. The auditory neuropathy in the two affected siblings is likely to be inherited as a recessive disorder.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:As part of an ongoing study of presbyacusis, the relationship between blood chemistry levels and hearing levels was investigated. Previous reports often used small sets of blood chemistry measures, and results were inconclusive. This experiment examined hearing levels and 27 measures of blood chemistry using various univariate and multivariate statistical procedures.Design:Blood from 89 female and 128 male human subjects was collected. Subjects' ages ranged from 60 to 82 yr, and hearing levels ranged from normal to moderate/severe. Subjects with a history of middle ear disease were excluded. Electrolyte panel (Na, K, Cl, CO2, Ca, urea nitrogen, glucose, creatinine, and Mg), hematology panel (WBC, RBC, Hgb, hematocrit, platelet, etc.), serum lipids (total cholesterol, low-density lipoprotein [LDL], and high-density lipoprotein [HDL]), immunoglobulins (IgG, IgA, IgM, and IgE), and thyroxine were analyzed using univariate and multivariate statistical procedures.Results:Blood chemistry levels of most subjects were within normal ranges as defined by our laboratory. Correlation between blood chemistry measures and pure-tone averages (PTAs) ranged from minimal to low. Results of factor analysis, discriminant analysis, and canonical analysis showed that combining blood chemistry measures from the same panel still could not predict PTA effectively. One exception to this was a gender-specific effect of cholesterol. Hearing levels of women with high LDL/HDL ratios were 5 dB better than those of women with low LDL/HDL ratios. The comparable difference in men was only 1 dB.Conclusion:Results suggest that blood chemistry measures that are primarily within the normal range have very little value in predicting pure-tone thresholds in older subjects.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:To determine the long-term psychological outcome of postlingually deafened adults who received multichannel cochlear implants and to relate the psychological outcome to audiological outcome.Design:Thirty-seven recipients of multichannel cochlear implants who participated in a prospective clinical trial completed psychological assessments before implantation and at regularly scheduled follow-ups through 54 mo of implant use. Standardized measures of affect, social function, and personality were used, and scores on these measures were correlated with asymptotic scores on several audiological measures.Results:Evidence of significant improvement on measures of loneliness, social anxiety, and distress were obtained within a year after implantation and throughout the duration of the follow-up period. For measures of assertiveness and marital satisfaction, improvement was apparent only after long-term implant use. Although favorable changes on the Minnesota Multiphasic Personality Inventory (MMPI) Depression Scale were evidenced only in the initial follow-up period, improvements on the MMPI Paranoia and Social Introversion Scales persisted throughout the 54 mo follow-up.Conclusion:Multichannel cochlear implant use is associated with long-term psychological benefit. Correlations between audiological outcome and psychological outcome, however, suggested that the relation between audiological benefit and psychological benefit is not simple.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objectives:1) To quantify the benefits of FM amplification for persons with severe and profound hearing loss; 2) to compare a body-worm and a behind-the-ear FM system; 3) to measure the effects of reducing FM microphone sensitivity relative to hearing aid sensitivity.Design:Recognition of phonemes in lists of consonant-vowel-consonant words was measured in 13 teenage students with severe and profound hearing loss. Presentation was by live voice at 10 feet from the listeners and 12 inches from the FM microphone/transmitter. Students listened: a) via a body-worn and a behind-the-ear system; b) with the FM microphone/transmitter on and off; c) in noise and in quiet. Systems were adjusted so that sinusoidal inputs of 65 dB SPL gave equal gains via the FM and hearing aid microphones. In a follow-up study, the gain via the FM microphone was reduced so that a sinusoidal input of 65 dB SPL into the hearing aid microphone produced the same output as a sinusoidal input of 80 dB into the FM microphone (as recommended inAmerican Speech-Language-Hearing Association, 1994).Results:1) Addition of the FM microphone signal to that available from the hearing aid microphone was equivalent, on average, to doubling the number of independent channels of information available to the listeners. 2) FM benefit was present in both quiet and noise but was somewhat greater in noise. 3) Contrary to prediction, however, noise interfered with phoneme recognition even under the aid+FM condition. 4) Differences between the body-worn and behind-the-ear systems were small, but there was a measurable advantage for the body-worn system under the aid+FM condition. 5) Reducing FM microphone sensitivity by 15 dB virtually eliminated the FM benefit. 6) Forty-four percent of the variance in phoneme recognition (averaged across listening conditions) could be explained by better-ear, three-frequency average pure-tone threshold. 7) Vowels were recognized more easily than consonants, and initial consonants were recognized more easily than final consonants, but the FM benefit was present for all three phonemes.Conclusions:The findings confirm the value of FM amplification for persons with severe and profound hearing loss, in both quiet and noise. The negative effects of noise were not completely eliminated, however, under the aid+FM condition. This finding can be attributed to a reduction of gain in the FM channel, when speech input was used, because of compression limiting in the microphone transmitter. The superiority of the body-worn system under the aid+FM condition suggests a need for higher saturation sound pressure level in the behind-the-ear system when used with persons having severe and profound hearing loss. The findings do not support use of an "equal output" criterion for adjusting relative gains via the FM and hearing aid microphones-at least for persons with very severe and profound hearing loss operating under the conditions tested in this study.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:To systematically investigate in normal-hearing listeners the effects of decreased audibility produced by broadband noise masking on the cortical event-related potentials (ERPs) N1, N2, and P3 to the speech sounds /ba/ and/da/.Design:Ten normal-hearing adult listeners actively (button-press response) discriminated the speech sounds /ba/ and /da/ presented in quiet (no masking) or with broadband masking noise (BBN), using an ERP oddball paradigm. The BBN was presented at 50, 60, and 70 dB SPL when speech sounds were presented at 65 dB ppe SPL and at 60, 70 and, 80 dB SPL when speech sounds were presented at 80 dB ppe SPL.Results:On average, the 50, 60, 70, and 80 dB SPL BBN maskers produced behavioral threshold elevations of 18, 25, 35, and 48 dB (average for 250 to 4000 Hz), respectively. The BBN maskers produced significant decreases (relative to quiet condition) in ERP amplitudes and behavioral discriminability. These decreases did not occur, however, until the noise masker intensity (in dB SPL) was equal to or greater than the speech stimulus intensity (in dB ppe SPL), that is, until speech to noise ratios (SNRs) were ≤0 dB. N1 remained present even after N2, P3, and behavioral discriminability were absent. In contrast to amplitudes, ERP and behavioral latencies showed significant decreases at higher (better) SNRs. Significant latency increases occurred when the noise maskers were within 10 to 20 dB of the stimuli (i.e., SNR ≤ 20 dB). The effects of masking were greater for responses to /da/ compared with /ba/. Latency increases occurred with less masking for N1 than for P3 or behavioral reaction time, with N2 falling in between.Conclusions:These results indicate that decreased audibility as a result of masking affects the various ERP peaks in a differential manner and that latencies are more sensitive indicators of these masking effects than are amplitudes.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:The purpose of this study was to compare the effects of monaural and binaural broadband masking noise on binaural interaction components (BICs) of the human auditory brain stem evoked potentials (ABEPs).Design:The BICs of the human ABEPs were studied by subtracting the potentials to binaural clicks from the algebraic sum of monaurally evoked potentials to clicks alone or to clicks with ipsilateral monaural or binaural broadband masking noise. Alternating polarity, 11/sec clicks were presented at 65 dB nHL, and noise was presented at 45 dB nHL. Analysis included peak-to-prestimulus baseline amplitudes and latencies of BICs' peaks and troughs from the vertex-mastoid (A) and vertex-neck (Z) channels. In addition, 3-channel Lissajous' trajectory (3-CLT) analysis, estimating the single, centrally located dipole equivalent of surface activity, was performed on data recorded from three orthogonally positioned electrode pairs. 3-CLT measures included apex latency, amplitude, and orientation, as well as planar segment duration, size, shape, and orientation.Results:All BICs 3-CLTs included five main components (labeled BdI, BdII, BdIII, BeI, and BeII). In general, apex latencies were longer with masking noise. However, BdIIand BeIapex latencies were shorter with binaural than with ipsilateral monaural masking noise. Apex amplitude and planar segment size of component BeI, as well as P1peak amplitude in BICs of the Z-channel records, were larger with binaural than with monaural noise. No significant difference between the monaural and binaural noise conditions was found in durations, shapes, and orientations of planar segments of BICs 3-CLT, nor in peak latency of BICs in the A- and Z-channel records.Conclusions:We suggest that these effects on the latency and amplitude of BICs reflect binaural processing in the human brain stem. In particular, the larger amplitudes and shorter latencies of P1and BeIwith binaural than with ipsilateral monaural masking may be associated with the psychophysical effect of binaural masking level difference.

ISSN:0196-0202    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Objective:To develop a measuring apparatus that has the ability to sweep both frequency and external auditory meatus static pressure and can display measurement results in a three-dimensional expression. To measure the middle ear dynamic characteristics of normal-hearing subjects and of patients with this apparatus.Design:Investigate 275 ears of 153 normal-hearing subjects and 72 ears with middle ear diseases.Results:The measurement results show fairly distinctive patterns depending on the middle ear conditions, i.e., normal, ossicular chain separation, ossicular chain fixation, secretory otitis media, tympanic membrane perforation, and tympanic membrane atelectasis. The evaluation of patients with ossicular diseases revealed that the rate of correct diagnosis of ossicular chain separation is 84% and that of ossicular chain fixation is 74%. These diagnoses were confirmed by surgery.Conclusion:Displaying the measurement results in a three-dimensional expression is helpful to make correct diagnosis in clinical practice. It is especially easy to make a distinction between the ossicular chain separation and ossicular chain fixation. Therefore, it is concluded that this apparatus has a high degree of clinical applicability to the diagnosis of these diseases.

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