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1/8. Acoustic trauma from the bone cutting burr.

    The amplitudes of the stapes footplate movements were determined in human temporal bones when the ossicular chain was drilled with a cutting and a diamond burr. High movements result in comparison to physiological data. The frequency distribution resembles the dB (A) curve. The intensity compared to sound pressure levels on the ear drum is higher than I30 dB. The pressure is constant over the period of contact between the burr and the ossicle. Most likely these unphysiologic movements of the stapes footplate can cause inner ear damage as we had to admit in a case of facial nerve decompression.
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ranking = 1
keywords = frequency
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2/8. High-frequency electrostimulation hearing after mastoidectomy.

    This study was undertaken to measure the degree of high-frequency sensorineural hearing loss following mastoid surgery. Twenty-five patients undergoing mastoidectomy procedures were tested preoperatively, less than 2 days postoperatively, and at 30 days postoperatively using the Tonndorf Audimax 500 high-frequency audiometer. Electrostimulation thresholds in 1-kHz intervals, from 1 to 20 kHz, were measured, and the highest detectable frequency was determined to within 0.1 kHz. Surgical drilling time was recorded. Average drilling time was 51 minutes. A significant temporary threshold shift was observed, measurable at multiple frequencies, less than 48 hours after mastoidectomy. There was no clinically significant change in electrostimulation thresholds (measured in 1-kHz increments, from 1 to 16 kHz) preoperatively to 30 days postoperatively. A statistically significant average loss of 0.89 kHz in the highest frequency producing a measurable response was noted (p less than 0.05). Determinations of the highest measurable frequency may be the most sensitive measure of surgically-induced, high-frequency sensorineural hearing changes.
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ranking = 10
keywords = frequency
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3/8. The need for a participatory conservation programme for the reduction of noise exposure to Thai female workers.

    hearing loss induced in thirty female workers because of exposure to continuous noise was studied in a plastic bag plant in Samutprakarn Province, the largest industrial zone in thailand. The sound level in this plant was 98.5 dBA., 94.0 dBA. and 93.0 dBA. in the weaving, winding and warping sections, respectively. Results of an audiometric test showed a significant relationship between high noise level and hearing loss at frequency 4,000 Hz. A questionnaire survey found that a relatively high number of workers had various symptoms such as: 76.7% general fatigue, 70% headache, 63.3% ear distension and 56.7% vertigo. Concerning the usage of ear protective devices, it was found that 80% of the workers have never used such devices, 16.7% occasionally used them, and 3.3% have always used cotton wool to reduce the high noise level. Their reasons for non-use of ear protective devices were 1) not provided by the employer (86.7%), 2) not necessary (83.3%), 3) accustomed to the noise (63.3%), 4) nobody uses (56.7%), and 5) no loud noise (16.7%). These results point to the need for improving the work conditions and welfare services of the workers at this plant. Also, hearing conservation programmes can be instituted in developing countries through cooperation among the safety inspectorate, the employer and the workers.
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ranking = 1
keywords = frequency
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4/8. Low-frequency sensorineural hearing loss. Brainstem response, speech and high-frequency audiometry.

    Four cases of acquired, unilateral sensorineural hearing loss are presented. The low-frequency octave threshold changes are considered compatible with the low-frequency tails of neurons with characteristic frequencies of 2, 4 and 9 kHz. Zero speech discrimination was found in two patients with high-frequency threshold preservation at and above 4 kHz. Normal auditory brainstem responses were obtained in the two patients with low-frequency hearing loss confined to the frequency bands below 2 and 4 kHz respectively. Only wave I could be reliably identified in the two patients with single frequency threshold preservation at 2 and 9 kHz, while both presented a second, low amplitude wave with latency corresponding to our normative values for wave V. The latter may represent a delayed and pathological wave III.
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ranking = 20.76630047916
keywords = wave, frequency
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5/8. High-frequency audiometry and noise-induced hearing loss.

    A group of noise-exposed male subjects with an audiogram that is characteristic for noise trauma were submitted to high-frequency audiometry (HFA) up to 20 000 HZ. The results were compared with those obtained in a group of normally hearing persons with no history of noise exposure. Conserved high frequency hearing was found. Very strict selection criteria were applied in both groups in order to avoid hereditary diseases and to ensure normal middle ear function. The findings are in good overall agreement with histological findings in noise-exposed animals and also with high-frequency studies in the older literature. Two illustrative case stories from patients with severe 4--6 kHz dips are reported, one with preserved high-frequency hearing in spite of a considerable acoustic trauma and one with extreme sensitivity towards noise and with no hearing at all in the high frequencies. It is concluded that 1) HFA cannot be used as an early indicator of the traumatic effect of high intensity noise; 2) presbycusis and noise damage may be additive elements in the older age groups (above 50 years); 3) persons with abnormal high-frequency hearing are possibly hypersensitive towards excessive noise and HFA might be useful in the routine audiological evaluation of workers before these are exposed to noise.
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ranking = 9
keywords = frequency
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6/8. work-related, noise-induced hearing loss: evaluation including evoked potential audiometry.

    This article reviews the evaluation of 246 workers (492 ears) who underwent otologic and audiologic testing as part of a worker's compensation claim for work-related, noise-induced hearing loss. tinnitus was present in 58% of the patients, but was rarely a major symptom. Other otologic symptoms or a history of ear disease were virtually nonexistent. Standard audiometry showed a downsloping, high-frequency sensorineural hearing loss in 85% of the ears tested, with only 37% having a characteristic "noise notch" at 4000 or 6000 hertz. Asymmetric hearing loss was not uncommon, with 48 patients (20%) undergoing magnetic resonance scanning, all of whom showed no central lesion responsible for the loss. Proven malingering was surprisingly uncommon (9%). In this study, evoked response audiometry was a valuable adjunct to confirm behavioral thresholds in the evaluation of possible work-related, noise-induced hearing loss. The middle latency response was more effective than the auditory brainstem response as a result of the high-frequency steepness of the audiometric curve.
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ranking = 2
keywords = frequency
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7/8. Age and the human cochlear traveling wave delay.

    OBJECTIVE: Cochlear physiologic changes that occur with aging also may affect the mechanics and filtering properties of the cochlea. In studying aging effects, it is also necessary to consider the effects of hearing threshold losses because thresholds generally increase with age, and threshold losses also affect the filtering properties of the cochlea. A distortion product emission (DPE)-based measurement of human cochlear traveling wave delays allows an indirect assessment of the mechanics of the traveling wave and how it might change with age. DESIGN: The cochlear traveling wave delay has been derived from DPE phase measurements using an f1 sweep paradigm (Kimberley, Brown, & Eggermont, 1993). In the present study, traveling wave delay was estimated from DPE phase measurements taken from the left ears of 91 subjects (22 to 78 yr) with auditory thresholds ranging from normal hearing (< or = 25 dB SPL, ANSI 1969) to mild cochlear hearing damage. No one under the age of 65 had hearing losses exceeding 40 dB SPL to 8 kHz. Pure-tone thresholds were determined at eight frequencies through a 4-interval, forced-choice, adaptive-level psychophysical test. DPE phase and amplitude measurements were made at these eight frequencies using CUBeDIS-related software (AT&T Bell Labs). Round-trip traveling wave estimates were calculated from the DPE phase measurements for each of the eight f2 frequencies (places). RESULTS: Traveling wave delays estimated using DPE phase were not significantly affected by mild hearing losses. Traveling wave delay, however, does increase slightly with age. Optimal f2/f1 ratio and associated DPE amplitude also were tested for age or threshold effects. The optimal f2/f1 ratio remained unaffected by age or hearing loss but decreased with increasing frequency. The maximum DPE amplitude decreased with both advancing age and increasing pure-tone threshold, so it was impossible to isolate the contribution of each individual factor. CONCLUSIONS: Mild hearing losses do not affect the round-trip traveling wave delay. There is a slight age dependence, however. This may suggest that there are age-related but threshold-independent factors that may alter such properties as basilar membrane stiffness or cochlear fluid composition. The relationship between maximum DPE amplitude and threshold, at the frequencies tested, is a better predictor of hearing thresholds than the DPE amplitude as obtained from a fixed ratio DPE amplitude measurement.
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ranking = 21.298901437479
keywords = wave, frequency
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8/8. growth behavior of the 2 f1-f2 distortion product otoacoustic emission in tinnitus.

    High-resolution hearing threshold and 2 f1-f2 distortion product otoacoustic emission (DP) were measured with the same in-the-ear sound probe and same calibration at 51 frequencies between 500 and 8000 Hz in 39 sensorineural hearing loss ears associated with tinnitus. Using a primary tone setting L1 = 0.4L2 39 that accounts for the nonlinear interaction of the two primary tones at the DP generation site at f2, DPs were elicited in a wide range from L2 = 65 to 20 dB SPL. We failed to find a uniform DP behavior in the 39 tinnitus ears tested. Seventeen of them behaved like impaired ears without tinnitus. In these ears a linearized DP growth was observed where the DP level decreased and the slope of the DP I/O functions steepened with increasing hearing loss and as a result both the DP level and the DP slope strongly correlated with hearing threshold. The other population, 22 tinnitus ears, exhibited a poor or even inverse relationship between DP level and hearing threshold, i.e., displayed an increase of DP level with increasing hearing loss. Despite the severe hearing loss but due to the high level, DPs could be recorded well in the frequency range that corresponded to the appearance of the tinnitus. The DP slope, however, increased with increasing hearing loss and, therefore, did still correlate with hearing threshold revealing pathological alteration. The data suggest that the DP level alone is hardly capable of assessing hearing impairment in tinnitus ears and may even be misleading. Thus just the DP slope seems to be the only reliable indicator of cochlear malfunction around the tinnitus frequency. The observed nonuniform DP behavior suggests different cochlear impairments in tinnitus ears. In those ears where the DP level decreases and the slope of the I/O functions increases with hearing loss, cochlear sensitivity and tuning are supposed to be diminished. In those ears where the DP level increases with increasing hearing loss, a reinforced mechanical distortion is hypothetized to be generated by cochlear hyperactivity that can be the source of both the abnormally high DP level and the tinnitus.
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ranking = 2
keywords = frequency
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