Audiology ; Auditory Threshold ; Humans

This study was performed to evaluate the effects on hearing of video tape manufacturing workers exposed to organic solvents. The experimental groups included solvents exposed group 51 and unexposed group 57 workers. All workers was examined air and bone conduction sensitivity by pure tone audiometer. The mean age of solvents exposed group was 34.1 and nonexposed group was 35.8. The mean duration of solvents exposed group was 7.3years. High frequency hearing loss prevalence of both groups was 23.5% in the group exposed to organic solvents and 17.5% in nonexposed group. There is no statistical significants in the prevalence of high frequency hearing loss. According to comparison of mean auditory threshold value by frequencies, on the air conduction test, right was statistically significant in the 250, 500, 1000, 2000, 4000Hz, except 8000Hz. Left 250, 500, 1000Hz was statistically significant. On the bone conduction test, left250, both 500, 1000, 2000, 4000Hz, except right 250Hz, was statistically significant difference. Generally, auditory sensitivity threshold of the exposed group was higher than the nonexposed group.
Auditory Threshold ; Bone Conduction ; Hearing Loss ; Hearing* ; Prevalence ; Solvents*

Animals ; Auditory Threshold ; Cochlea ; physiology ; Ear, Middle ; surgery ; Evoked Potentials, Auditory, Brain Stem ; Female ; Male ; Rats

OBJECTIVETo estimate tone-pip auditory brainstem response (tone-pip ABR) and auditory steady-state response (ASSR) thresholds to follow the development of hearing in four groups of normal babies through the first 6 month of life and to make a comparison between the tone-pip ABR and ASSR for 0.25 - 8 kHz frequency range at different groups.

METHODSThe tone-pip ABR and ASSR were recorded in four groups of normal hearing infants (160 ears) at the age of 2 - 4 day, 6 weeks, 3-month and 6-month. Tone-pip ABR and ASSR thresholds were established in 0.25, 0.5, 1, 2, 4 and 8 kHz stimuli.

RESULTSFor click ABR, the wave latency of I, III, V and inter-wave latency of I-III, III-V and I-V decreased as the age increase. The developmental changes were obvious in wave I and III before 6 weeks and 3 months respectively. Tone-pip ABR had the similar waveform as the click ABR. With the frequency increasing, their waveforms and wave latencies of I, III and V were getting better and shorter respectively. There was significant difference between the thresholds of tone-pip ABR and ASSR (all P < 0.05). The tone-pip ABR thresholds were significantly lower than those of ASSR from 0.5 to 8 kHz. Both ASSR and tone-pip ABR had similar audiograms for different age of infants with normal hearing.

CONCLUSIONSThe longitudinal findings presented in this study suggest that with the maturational development, the wave latency of I, III, V and inter-wave latency of I-III, III-V and I-V of tone-pip ABR decrease as the age increase, while the hearing sensitivity have no changes. Both tone-pip ABR and ASSR have stable frequency specificity. Compared to the ASSR, tone-pip ABR have lower response threshold and maybe nearer to the hearing level of the infant.

BACKGROUND AND OBJECTIVES: The aim of this study is to assess the correlation between the threshold of click-evoked auditory brainstem response (ABR) and the pure-tone averages in various formulas. SUBJECTS AND METHOD: Data were obtained from 207 patients (326 ears) with sudden sensorineural hearing loss. All subjects underwent hearing threshold evaluation using pure tone audiogram (PTA), speech audiogram and click-evoked ABR. Linear regression analyses were applied to assess the relation between threshold of click-evoked ABR and threshold of separate frequencies of the PTA and to analyze the correlation between threshold for click-evoked ABR and various pure-tone averages. RESULTS: Results revealed a significant relation between the threshold of click-evoked ABR and PTA thresholds at 0.5 kHz, 1 kHz, 2 kHz, 3 kHz, and 4 kHz. The highest coefficients of regression and determination were 1.026 for 4 kHz and R2=0.663 for 3 kHz, respectively. The coefficient of regression was highest (=0.995) for the mean of PTA thresholds for 3 kHz and 4 kHz. The coefficient of determination was highest for the mean of PTA thresholds for 1, 2, 3 and 4 kHz (R2=0.732). Multiple regression analysis showed a significant relation between the ABR threshold and PTA thresholds for 1, 3, and 4 kHz (R2=0.732), with highest correlation coefficient at 3 kHz [ABR=11.79+(0.17x1 kHz)+(0.26x3 kHz)+(0.23x4 kHz), (p<0.05)]. CONCLUSION: The threshold of click-evoked ABR correlates best with the mean of PTA thresholds for 1, 2, 3 and 4 kHz. The PTA threshold for 3 kHz has highest correlation with the ABR threshold.
Auditory Threshold ; Evoked Potentials, Auditory, Brain Stem ; Hearing ; Hearing Loss, Sensorineural ; Humans ; Linear Models

In order to explore the possible mechanisms by which ethologically relevant sounds can be extracted from complex auditory environments, this study examined the effects of weak noise on the rate-intensity functions (RIFs) of neurons responding to tone burst in the inferior colliculus (IC) of nine mice (Mus musculus Km). Under free field stimuli conditions, a total of 112 IC neurons were recorded. RIFs with and without simultaneous presentation of weak noise, of which the intensity was relative to 5 dB below minimum threshold of tone burst, were measured in 44 IC neurons. By means of evaluating the changes of dynamic range (DR), slope of RIFs, and percent inhibition at different tone burst intensities evoked by the weak noise, three types of variations in RIFs were observed, i. e., inhibition (39/44, 88.6%), facilitation (2/44, 4.6%), and no effectiveness (3/44, 6.8%). Statistical analysis indicated that only inhibitory effect of weak noise was significant (P< 0.001, n = 39). The inhibitory effect of weak noise was greater at lower stimulus intensity of tone burst but decreased significantly with increased stimulus intensity (P< 0.0001, n = 39). In addition, the DR and slope of RIFs became narrower and steeper with weak noise presentation, respectively (P< 0.01, n = 31). The results from the present study suggest that weak noise exerts a dynamic modulatory action on acoustical intensity sensitivity of IC neurons, which possibly leads to a better understanding of neural mechanisms underlying the extraction of sound signals from natural auditory scenes.
Acoustic Stimulation ; Animals ; Auditory Perception ; physiology ; Auditory Threshold ; physiology ; Inferior Colliculi ; physiology ; Mice ; Neurons ; physiology ; Noise

BACKGROUND AND OBJECTIVES: The aim of this study is to assess the correlation between hearing thresholds in pure tone audiometry (PTA) and auditory steady state response (ASSR) according to the hearing level and frequency. SUBJECTS AND METHOD: A total of 105 subjects (178 ears, 64 male and 41 female) were enrolled in this study. None of the subjects had middle ear diseases and PTA and ASSR were performed on the same day for each subject. Ninety-eight subjects (168 ears) were finally enrolled in the analysis of this study. RESULTS: The correlation coefficient (r) of mean hearing threshold between PTA and ASSR was 0.96 and the mean hearing threshold of PTA can be calculated from the mean hearing threshold of ASSR (PTA=1.05 x ASSR-7.6). When analyzed according to frequency, the correlation coefficients were 0.94, 0.95, 0.94, and 0.92 for 500, 1,000, 2,000, and 4,000 Hz panels, respectively. CONCLUSION: This study showed that ASSR and PTA had very close correlation and ASSR could be used to estimate hearing thresholds with reliable accuracy in various cases where subjective hearing measurement including PTA could not be performed.
Audiometry* ; Auditory Threshold ; Ear ; Ear, Middle ; Evoked Potentials, Auditory, Brain Stem ; Hearing* ; Humans ; Male

OBJECTIVE: The latency-intensity function (LIF) of wave V from click ABR of some deaf children showed great variation. We attempted to find out the intrinsic reasons. METHOD: The children recieved tone-burst ABR test. RESULT: Frequencies from 0.5-4.0 kHz have been tested and the thresholds of tone-burst ABR were recorded. The average thresholds of steeply LIF children at 0.5-4.0 kHz were (93.13 ± 7.04), (79.37 ± 7.72), (69.38 ± 8.54) (66.25 ± 8.06) dB respectively, while the average thresholds of shallower LIF children at these 4 frequencies were (65.00 ± 7.32) (68.13 ± 6.55) (70.63 ± 6.80) (78.12 ± 8.34) dB respectively. CONCLUSION The results imply that the child with steeply LIF may have more hearing loss at frequencies 0.5 and 1 kHz than those with shallower LIF. LIF may predict the audiogram configuration.
Audiometry, Pure-Tone ; Auditory Threshold ; Child ; Evoked Potentials, Auditory, Brain Stem ; Hearing Loss ; diagnosis ; Humans

OBJECTIVE: To investigate the auditory characteristics of guinea pigs immunized with purified P0 protein from inner ear of guinea pigs. METHOD: Purified inner ear P0 protein was made by Preparative SDS-PAGE. To evaluate the results of Auditory Brainstem Response (ABR), Compound Action Potention (CAP), and Distortion Product Oto-acoustic Emissions (DPOAE) in guinea pigs immunized with purified guinea pigs inner ear myelin protein P0. RESULT: Seven ears of the guinea pigs immunized with purified inner ear P0 protein developed hearing loss. In the ABR study, peak latencies of wave I, III and the interpeak latency of I -III, I-IV were elevated in this group of guinea pigs compared with the control group (P < 0.01). But the interpeak latency of III-IV did not change. In the CAP study, the threshold elevated and latency prolonged (P < 0.01). No significant change of DPOAE was found in the P0-sensitized guinea pigs when compared to controls (P > 0.05). Even though the contra-lateral suppressive effect had the depressed tendency, but there was no significant different when compared with the controls (P > 0.05). CONCLUSION Purified inner ear P0 protein is an important autoimmune inner ear antigen and can develop autoimmune disease of the auditory nerve.
Animals ; Auditory Threshold ; Evoked Potentials, Auditory, Brain Stem ; physiology ; Guinea Pigs ; Immunization ; Myelin P0 Protein ; immunology

Humans ; Auditory Pathways ; Hearing Loss, Sensorineural ; Cochlear Implantation ; Cochlear Implants ; Hearing Loss, Central ; Auditory Threshold ; Evoked Potentials, Auditory, Brain Stem