• Phonetics and Speech Sciences
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• v.1 no.3
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• pp.151-154
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• 2009

The external ear generates resonance gain because of anatomical characteristics. The ear canal resonance is influenced by the length and volume of the ear canal, the pinna, the concha cavity, the body trunk, and the speed of sound wave. This study is focus on the influence of the volume of ear canal. 17-healthy-adult (32 ears) were participated. They did not have any medical and ear disease history. The maximum resonance frequency of the ear canal was 2675 (${\pm}265$) Hz at azimuth $0^{\circ}$ and 2784 (${\pm}268$) Hz at azimuth $45^{\circ}$. The resonance gain was 18.1 (${\pm}3.9$) dB at azimuth $0^{\circ}$ and 17.9 (${\pm}3.8$) dB at azimuth $45^{\circ}$, respectively. The ear canal volume was 0.78 (${\pm}0.2$) cc and 1.32 (${\pm}0.8$) cc including static compliance. The ear canal resonance was changed depending on the ear canal volume. It was also statistically correlated at azimuth $0^{\circ}$ (p=0.038) and $45^{\circ}$ (p=0.013), respectively. The resonance gain was not correlated with the ear canal volume. The change of resonance frequency according to the ear canal volume will be useful information in the field of audiological rehabilitation especially for hearing aids fitting. In addition, we expected this study can provide the basic information for the study of the external ear resonance characteristics.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.4
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• pp.363-370
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• 2017

In this paper, we proposed a low-complexity speech enhancement algorithm based on a improved minima controlled recursive averaging (IMCRA) and log minimum mean square error (logMMSE). The IMCRA algorithm track the minima value of input power within buffers in local window and identify the speech presence using ratio between input power and its minima value. In this process, many number of operations are required. To reduce the number of operations of IMCRA algorithm, minima value is tracked using time-varying frequency-dependent smoothing based on speech presence probability. The proposed algorithm enhanced speech quality by 2.778%, 3.481%, 2.980% and 2.162% in 0, 5, 10 and 15dB SNR respectively and reduced computational complexity by average 9.570%.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.137-140
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• 1999

본 논문에서는 디지털 보청기의 자동보정법을 제안하고 이를 이용하여 구현한 보정시스템에 대하여 기술한다. 일반적으로 난청환자의 청각 손실은 전 주파수를 걸쳐 일정하게 발생하는 것이 아니라, 고음 또는 저음 등 일부 특정 주파수 대역의 청각특성의 이득이 다른 주파수에 비해 상대적으로 낮아져서 생기는 현상이다. 그러나 현재까지의 보청기는 이와 같은 청각 손실을 가지고 있는 환자들에 대하여 전 주파수 대역의 음압을 동일 비율로 높여주는 문제가 있다. 이와 같은 보청기로 보정하게 되면, 주파수 대역별 균형이 맞지 않기 때문에 소리가 변형되어 들리게 되고, 명료도 또한 떨어지게 된다. 또한, 기존의 아날로그보청기는 생산공정 중에 잡음 피크 제거, 리미터 조정, 이득 조정(GC) 등의 작업을 수동으로 수행하게 되는데, 이는 작업공정이 복잡하고 개개인에 청각특성에 맞는 정확한 보정이 불가능한 문제점을 안고있다. 이와 같은 문제점을 해결하기 위하여 제안한 자동보정 시스템은 각 주파수 대역별 최적화된 파라미터를 자동적으로 찾아서 입력하므로 보다 정확하고 신속한 보정이 가능하게 된다. 이 시스템은 외부 IC 콘트를 장치인 Hl-PRO를 이용하여 PC 환경 하에서Visual Basic으로 구현하였으며 시스템의 출력값을 측정하여 검토한 결과 구현한 자동보정법이 유효함을 확인할 수 있었다.

• Journal of Korean Academic Society of Home Health Care Nursing
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• v.22 no.1
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• pp.47-58
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• 2015

Purpose: This study was aimed at understanding meal services provided at long-term care facilities. Method: Interview survey was conducted using questionnaires at 254 facilities located in the Kyung-In area. Result: Of the residents, 37.4% were eating meals unassisted. Eating places included living rooms and residents' rooms in most facilities. Major noise source was television in 63.8%. Apron was applied to all elderly residents at mealtimes in 49.6% of the facilities. Half of the facilities used feeding utensils except for ordinary spoon and chopsticks. Of the facilities having individual prosthetic devices, dentures were applied before eating in 98%, glasses in 20.2% and hearing aids in 9.2%. Most facilities included the residents' favorite foods in menu: wheres, only 9.4% offered the menu which residents could choose. Conclusion: Standard guidelines and staff education for meal services need to be provided for elderly residents.

• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.262-268
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• 2013

The performances of speech compression schemes appeared to be dependent on the response profiles to compressed stimuli and the features of individual languages to some extent. Although these response profiles were critical in comparing various compression outcomes, the related data were limited in number for Korean monosyllabic words. From the previous study, data from PNT (Preserving No Trait) compression was selected as a base set for comparison. In this study, the outcomes from PPT (Preserving Pitch Trait) and PTT (Preserving Time Trait) were analyzed under the same condition. Then, the properties of these three widely used representative compression schemes were quantitatively compared in normal hearing adults (N=20) for controlled Korean quintet digit sets (0 through 9). Results showed that PPT compression scheme exhibited the best perceptual performances for the Korean quintet digit sets in the final outcomes (PPT>PTT>PNT). The compression ratios of 50% performances were estimated as about 20%, 42%, and 44% for PPT, PTT, and PNT, respectively. The data indicated the influences of the salient psychoacoustic features of the three representative compressions on perceiving Korean monosyllabic digit words. This controlled procedure with monosyllabic quintet sets can evaluate efficiency and effectiveness of other compression schemes and may also contribute to diagnosing auditory processing disorders and fitting special hearing aids with compression issues.

• Journal of Korea Multimedia Society
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• v.21 no.6
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• pp.678-684
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• 2018

In order to broaden the indication of middle ear implant, research has been actively conducted on the reverse output method that stimulates the round window. However, it is very difficult to transmit the vibration output effectively because the indivisual anatomical difference of the round window niche is very large and also the visual field is not secured even by a skilled otolaryngologic surgeon. In this paper, we propose a new reverse stimulation method of middle ear implants that transmits energy to the inner ear by using air as a medium. This can compensate for the disadvantages of the conventional method of transmitting vibration energy and minimizes the energy transfer efficiency interference due to the combination of the excitation point and the output device. It was shown that forward and backward transfer characteristics were obtained by cadaveric experiments, and it was shown that it can overcome the acoustical impedance of high round window and transmit energy to inner ear. The receiver, which is the output device of the conventional hearing aids, can generate a constant volume velocity, so it can have a high output at a limited volume, such as a round window niche. So, suggested method can overcome the high acoustical impedance of the round window and deliver acoustic energy to the inner ear.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.5
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• pp.924-930
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• 2015

In this paper, we propose a novel approach of low computational complexity to improve the speech quality of the small acoustic equipment in noisy environment. The conventional gain control algorithm suppresses the noise of input signal, and then the part of wide dynamic range compression (WDRC) amplifies the undesired signal. The proposed algorithm controls the gain of hearing aids according to speech present probability by using the output of a voice activity detection (VAD). The performance of the proposed scheme is evaluated under various noise conditions by using objective measurement and yields superior results compared with the conventional algorithm.

• Journal of Sensor Science and Technology
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• v.13 no.1
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• pp.12-19
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• 2004

The tinnitus which is the one of the auditory disease is a phenomenon that the patients feel the sound in the ear or the head when there is no sound sources. There have been many therapies for this tinnitus so far, but it is known that the TRT (Tinnitus Retraining Therapy) is the most effective therapy. So we designed and developed the controllable white noise generator for TRT. It must be designed as small as possible for user's convenience, such as the ITE (In The Ear) type hearing aids. It used the thermal noise as the white noise source. And filter and tone control circuits are used at the end of the noise generation part to control the white noise characteristics. This link of the controllable circuits is used to change the white noise's characteristic for the various tinnitus patients' characteristic. we can confirm that the designed and implemented controllable white noise generator which is a ITE type operates properly by the experiments of filter and tone control circuit.

• Journal of Preventive Medicine and Public Health
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• v.5 no.1
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• pp.115-123
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• 1972

As a link of chain study program of school health, a survey was made up by the screening test with audiometry for hearing disturbance on 18,675 high school students who are mainly aged in 15-19 years from November 5.1969 to October 30. 1970. The results obtained were summerized as follows. According to our criteria as table 3, the rates of the profound, the severe and the moderate who required the appropriate hearing aids were 0.02%, 0.03% and 0.14% respectively:-the cumulative percentage was 0.197. When the marginal, 0.23% should be included the cumulative rate was 0.41%. But there was no-significance by sex and school classes. If we will make the special classes for them one class would be estimated out of 10,000 persons when a class is formed with about 15 persons. Otherwise when we examined that according to each ear of persons, the rates of the profound, the severe and the moderate were 0.17%, 0.22% and 0.33% respectively and their cumulative percentage wag 0.72. There was no significance also by sex and age. By the way, the rate of hearing disturbance in urban high school students tended to lower than rural. And the perceptive disturbance was higher than rural in rate. The conductive disturbance tended to oppose in comparison with the above.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.1
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• pp.93-108
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• 2016

One of the fields to which the 3D printing technology can be applied is the field of medicine. Recently, the application of 3D printing technology to the bio-medical field has been gradually increasing with the commercializing of the bio-compatible or bio-degradable materials. The technology is currently contributing to the biomedical field by reducing times required for operations or minimizing adverse effects through preoperative identification of post-surgical consequences or model surgery with artificial bones and organs. This technology also enables the production of customized biomedical auxiliary products like hearing aids or artificial legs etc. For the field of dentistry, the 3D printing technology is also expected to elevate the level of dental treatment by making the customized orthodontic models, crown, bridge, inlay, and surgical guides for implant and surgery. However, issues remaining unidentified or incomplete in printing materials, modeling technology, software technology associated with CAD, verification of bio-stability and bio-effectiveness of materials or in compatibility and standardization of the technology are yet to be solved or be clarified for the full-scale application of the 3D printing technology, thus, it seems such issues should be resolved through further studies.