• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.415-418
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• 2005

DSP chip parameters of a digital hearing aid (HA) should be optimally selected or fitted for hearing impaired persons. The more precise parameter fitting guarantees the better compensation of the hearing loss (HL). Digital HAs adopt DSP chips for more precise fitting of various HL threshold curve patterns. A specific DSP chip such as Gennum GB3211 was designed and manufactured in order to match up to about 4.7 billion different possible HL cases with combination of 7 limited parameters. This paper deals with a digital HA fitting program which is developed for optimal fitting of GB3211 DSP chip parameters. The fitting program has completed feature from audiogram input to DSP chip interface. The compensation effects of the microphone and the receiver are also included. The paper shows some application examples.

• Journal of Preventive Medicine and Public Health
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• v.32 no.1
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• pp.30-39
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• 1999

Objectives. This study was carried out to evaluate hearing impairment judgement and to investigate the differences in various diagnostic criteria for noise-induced hearing loss (NIHL) among workers who required for close observation (C). Methods. Out of 731,029 workers who had taken the specific periodic health examination in 1994, we used the audiometric data on 37,999 workers (C) eliminating the employees who had previous otologic problems. Many investigators have being using different criteria for the evaluation of hearing impairment. In this study, we used the criteria of early (1989-1994), current, compensation for NIHL in Korea, 2-, 3-, 4-divided classification and hearing loss at 4,000 Hz and compared the evaluation results. Results. The prevalences of C and workers who had occupational disease $(D_1)$ diagnosed for NIHL were 11.1 % and 0.44 %. There were significant difference in the prevalences of C and $D_1$, depending on different province of Korea. Pure tone averages (PTAs) were not appropriately applied in their evaluation 97% of workers whom we studied on were below the level of mild hearing loss judged by ISO standard. However, there were wide variations in the prevalence rate of mild hearing loss by diagnostic criteria. Thus, there were different judgements in determining the degree of NIHL depending on which diagnostic criteria were utilized. PTAs were found 20.54 (Rt) and 20.74 (Lt) when the method of 3-divided classification was applied for audiometric data. The degree of hearing impairment of the left ear was more severe than that of right ear. The prevalence of normal hearing threshold below 20 dB was 75.4% and the range of difference in both ear was below 10 dB. Right sided hearing threshold levels were 21.08 dB (500 Hz), 18.44 dB (1,000 Hz), 22.09 (2,000 Hz) and 52.36 dB (4,000 Hz). There was typical high frequency loss (C5-dip at 4,000 Hz) above 30 - 40 dB in normal hearing level. The increasing trend in hearing threshold level was gradually decreased by the increase of PTAs. The difference between PTAs and threshold at 4,000 Hz was about 10 dB. Conclusions. We could found that PTAs in the previous examination were not appropriately evaluated. This study revealed that they did not use unique criteria for managing the workers of NIHL. For the prevention of NIHL, it was found that the quality control on diagnosis and comprehensive management program were required, especially for those of hearing loss (C).

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• v.61 no.11
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• pp.573-579
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• 2018

Background and Objectives Cochlear dead region (CDR) is a region in the cochlear where hearing loss has occurred due to damage to the inner hair cells and/or neurons. Recently, a subjective test involving a pure-tone test in the presence of threshold-equalizing noise (TEN) was introduced to identify CDR. However, for uncooperative patients, such a subjective method would be unsuitable and objective methods would be needed instead to detect CDR. The acoustic change complex (ACC) is an evoked potential elicited by changes in the ongoing sound. In this study, we developed an objective method of identifying CDR by combining ACC response with a TEN test, namely the TEN-ACC test, and investigated its feasibility in normal-hearing listeners. Subjects and Method Ten normal-hearing subjects participated in this study. All subjects underwent both behavioral TEN test and electrophysiological TEN-ACC test. The stimuli for the TEN-ACC test consisted of TEN and embedded pure tones with different frequencies/signals to noise ratios (SNRs). To identify the thresholds, the range SNR of stimulation was varied from 0 to 20 dB, in stages of 4 dB. Results The ACC responses of all subjects who participated in this study were well elicited by stimuli developed for the TEN-ACC test. We confirm that the pure-tones embedded in TEN elicited the objective ACC response. Conclusion The results of this study suggest that the novel TEN-ACC test can be applied to evoke ACC in normal-hearing listeners. Future research should incorporate hearing-impaired listeners to determine the feasibility of the TEN-ACC test as an objective method to identify CDR.

• Journal of Ginseng Research
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• v.34 no.4
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• pp.336-341
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• 2010

One mechanism of inner ear damage by noise-induced hearing loss (NIHL) is the production of reactive oxygen species (ROS). Because Korean red ginseng (KRG) has an anti-ROS effect in various tissues, KRG may have a role in preventing NIHL. A window period exists in which ROS formations continue after noise exposure, and further damage can be prevented by antioxidants. In this study, we aimed to investigate the effects of KRG after exposure to noise. KRG (200 mg/kg) was fed to mice for 3 days after noise exposure. The change in hearing level was analyzed by measuring the auditory brainstem response. To induce a temporary threshold shift (TTS) of hearing, mice were exposed to 110 dB white noise for 3 hours. Fast recovery of hearing was observed in mice fed KRG 1 hour and 1 day after noise exposure for 3 days. The expression of 8-oxoguanine was not observed in the inner ears of mice fed KRG 1 hour after noise exposure, but was evident in the stria vascularis of mice in the control group (noise exposure only). From this study, we conclude that KRG acted as an effective inhibitor of NIHL in TTS cases.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.383-386
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• 2009

Todays, many young people suffer from noise-induced hearing loss by using wearable hearing devices, such as Bluetooth headset. This paper present hearing loss reduction algorithms considering individual hearing characteristics and threshold of feeling for Bluetooth headset. Experimental results using CSR Bluetooth headset example design board(DEV-PC-1645) show that individuals may be able to perceive without the inconvenience at the less sound intensity and the more sensitive frequency bands. As a result, we may prevent hearing loss to reduce excessive sound energy in each frequency bands.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1157-1164
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• 2007

In this paper, we implement a PDA(Personal Digital Assistant)-based audiometric system in order to estimate hearing threshold by adopting both pure-tone sound and speech audiometric test system. To estimate a subject's hearing threshold in an ambulatory audiometric test environment, an efficient sound calibration scheme between a PDA and a headphone device is proposed by appling polynomial fitting algorithms in 8-banded frequency ranges.

• The Journal of the Acoustical Society of Korea
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• v.24 no.5
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• pp.238-247
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• 2005

In this Paper. we Presents subband design techniques of a compensating filter and adaptive feedback canceller for the digital hearing aid. The sensorineural hearing loss has a hearing threshold that shows a nonlinear characteristic in frequency domain. and its compensation suffers from an echo that produced by an undesired time varying feedback path. Therefore. the digital hearing aid requires the compensator that can adjust gains nonlinearly in frequency bands and eliminate the echo rapidly In the Proposed digital hearing aid. the compensating filter is designed by the adaptive system identification method in subband structure, and the adaptive feedback canceller is designed by the subband affine projection algorithm. The designed compensation filter can control the nonlinear gain in each subband respectively, therefore precise compensation is possible. And the feedback canceller using the subband adaptive filter achieves fast convergence rate. The Performances of the Proposed method are verified by computer simulations as comparing with the behaviors of the previous trials.

• Journal of Audiology & Otology
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• v.25 no.3
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• pp.146-151
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• 2021

Background and Objectives: The relationship between hearing aid (HA) use and improvement in cognitive function is not fully known. This study aimed to determine whether HAs could recover temporal resolution or hearing in noise functions. Materials and Methods: We designed a prospective study with two groups: HA users and controls. Patients older than 45 years, with a pure tone average threshold of worse than 40 dB and a speech discrimination score better than 60% in both ears were eligible. Central auditory processing tests and hearing in noise tests (HINTs) were evaluated at the beginning of the study and 1, 3, 6, and 12 months after the use of a monaural HA in the HA group compared to the control group. The changes in the evaluation parameters were statistically analyzed using the linear mixed model. Results: A total of 26 participants (13 in the HA and 13 in the control group) were included in this study. The frequency (p<0.01) and duration test (p=0.02) scores showed significant improvements in the HA group after 1 year, while the HINT scores showed no significant change. Conclusions: After using an HA for one year, patients performed better on temporal resolution tests. No improvement was documented with regard to hearing in noise.

• Korean Journal of Audiology
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• v.25 no.3
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• pp.146-151
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• 2021

Background and Objectives: The relationship between hearing aid (HA) use and improvement in cognitive function is not fully known. This study aimed to determine whether HAs could recover temporal resolution or hearing in noise functions. Materials and Methods: We designed a prospective study with two groups: HA users and controls. Patients older than 45 years, with a pure tone average threshold of worse than 40 dB and a speech discrimination score better than 60% in both ears were eligible. Central auditory processing tests and hearing in noise tests (HINTs) were evaluated at the beginning of the study and 1, 3, 6, and 12 months after the use of a monaural HA in the HA group compared to the control group. The changes in the evaluation parameters were statistically analyzed using the linear mixed model. Results: A total of 26 participants (13 in the HA and 13 in the control group) were included in this study. The frequency (p<0.01) and duration test (p=0.02) scores showed significant improvements in the HA group after 1 year, while the HINT scores showed no significant change. Conclusions: After using an HA for one year, patients performed better on temporal resolution tests. No improvement was documented with regard to hearing in noise.

• Journal of Biomedical Engineering Research
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• v.31 no.5
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• pp.385-394
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• 2010

Automatic gain control(AGC) is used in hearing aids to compensate for the hearing level as to reduced dynamic range. AGC is consisted of the main 4 factors which are compression threshold, compression ratio, attack time, and release time. This study especially focus on each individual need for optimum release time parameters that can be changed within 7 certain range such as 12, 64, 128, 512, 2094, and 4096ms. To estimate the effect of various release time in AGC, twelve normal hearing and twelve hearing impaired listeners are participated. The stimuli are used by one syllable and sentence which have the same acoustic energy respectively. Then, each of score of the word recognition score is checked in quiet and noise conditions. As a result, it is verified that most people have the different best recognition score on specific release time. Also, if hearing aids is set by the optimum release time in each person, it is helpful in speech recognition and discrimination.