• Journal of KSNVE
• /
• v.9 no.5
• /
• pp.1005-1011
• /
• 1999

Generation of hole-tones and the instability of circular impinging jets are investigated based on the frequency characteristics and the radiated sound field. The experiment is carried out with varying hole sizes, jet speeds and impinging distances. It is found that hole-tones occur by both the low-speed laminar jet and the high-speed turbulent jet, but not by the transient jet, while plate-tones without holes are produced only in the high-speed turbulent impinging jet. When the diameter ratio of the hole to the nozzle is nearly one, hole-tones occur most easily. At low speed, it is found that hole-tones are due to the symmetrical unstable jet and the impinging distance decreases with jet speed. And the Strouhal number and the sound pressure level increase with jet speed. At high speed, hole-tones show the same characteristics as plate-tones. It is found that the ratio of the convection speed varies with the Strouhal number and the jet speed.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 1987.05a
• /
• pp.8.1-8
• /
• 1987

청신경종은 제8 뇌신경에서 기원하는 종양으로서 초기에 발견될수록 제거가 용이하기 때문에 조기진단이 중요한 의미를 갖는다. 뇌간유발반응검사는 청신경종의 초기에 객관적으로 청신경종의 유무를 확인할 수 있는 방법으로 사용되고 있다. 이에 저자들은 1982년부터 1986년까지 본원 이비인후과와 신경외과에 입원하여 수술한 청신경종 환자 27례에 대하여 뇌간유발반응검사를 검토하고 다음과 같은 결과를 얻었다. 27례중 9례에서 환측에서 제 1파만이 관찰되었고 이중 6례는 순음청력검사상 60 ㏈이하의 역치를 보였다. 13례에서는 환측의 반응이 전혀 없었고 5례에서는 양측에 이상이 있었다. 대개의 경우 진행된 상태에서 발견되어 수술을 시행했기 때문에 뇌간유발반응 검사상 특이 소견을 찾기 어려웠으나 청력이 남아 있는 감각신경성난청환자에 있어서는 진단적 의의가 있음을 알 수 있었다.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 1977.06a
• /
• pp.5.1-5
• /
• 1977

Since Metz first introduced the conceps of Impedance Audiometry in 1946. Many pioneers studied for the development of the acoustic Impedance bridge. It is now widely used in clinical audiology and it plays an important role in otology. Recently there was the literature stated on normal value of various test c Impedance. This paper is dealing with the clinical evaluation of type c in comparison with following subjects as; 1. Comparison with the otoscopic finding. 2. Correlation with the pure tone audiometry. 3. Correlation with the stapedial reflex. 4. Correlation between pathologic negative pressure range and middle ear fluid.

• Proceedings of the KOR-BRONCHOESO Conference
• /
• 1983.05a
• /
• pp.20-20
• /
• 1983

A 40-year-old man was admitted with chief complaints of sudden hearing loss, ear fullness and tinnitus of 12 days duration developed following SCUBA diving. An exploratory tympanotomy was done on 16th day of onset, and a small leakage of clear fluid was found on the anterior portion of the stapediovestibular joint, which was sealed off by small piece of fatty tissue from the ear lobe. Postoperatively, his PTA's was improved from 85㏈ to 15㏈, however high tone was remained unchanged above 4KHz. More exploration of the middle ear will be helpful to find the labyrinthine fistula causing sudden type of hearing loss.

• Journal of Sensor Science and Technology
• /
• v.28 no.5
• /
• pp.289-293
• /
• 2019

This paper presents a remote patient monitoring system for diagnostic pure-tone audiometry. A pure-tone audiometer was developed for basic hearing screening; its performance was evaluated according to international standards in terms of linearity, accuracy, and total harmonic distortion. Pure-tone audiometry has a maximum hearing level of 104.9 dB HL that is comparable with other commercial products. The audiometer shows satisfactory linearity with a deviation of ${\pm}0.4dB$, an accuracy of ${\pm}0.025%$, and a total harmonic distortion (THD) of 0.21%. The remote patient monitoring systems include remote control devices based on wide area network (WAN) connections and an audiometer connected in series. Through experimentation, we successfully performed real-time diagnostic communication without delay in transferring audiometric data. This system is expected to supply domestic equipment in the audiometric market and to improve the quality of life of patients in non-clinical environments.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2008.11a
• /
• pp.137-140
• /
• 2008

현대 사회는 육체적·정신적 활동을 많이 요구하게 되며 이러한 현상으로 스트레스의 증가와 이유없는 증후군의 발병이 점차 확대되고 있다. 특히 스트레스로 인한 피로의 누적으로 인체의 혈액 농도 및 순환에 영향을 끼치게 되며 이로 인해 신장의 상태가 악화될 수 있다. 따라서 신장의 이상 유무를 조기에 판단하여 적절한 조치를 취하는 것이 무엇보다 중요하다. 이를 위해 본 논문에서는 신장 질환을 앓고 있는 환자와 정상인을 대상으로 피실험자 집단군을 각각 구성하고 음성 정보의 형태학적 분석과 수치학적 분석을 실험으로 출력하고 결과값에 대해 비교·분석을 행하고자 한다. 최종적으로 실험을 통해 신장과 음성과의 관계를 정립하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.6
• /
• pp.2225-2233
• /
• 2010

Current puretone audiometer takes an operation model, so called face-to-face model, in which model an audiometrist assesses only one subject at a time. Such model results in high cost and long waiting time when there exist many patients. In order to solve such a disadvantage of face-to-face model, we have developed PC-based audiometer supporting client/server model, in which model one audiometrist is able to measure several subjects concurrently. This model has an architecture like that several PCs for subjects are connected to an audiometrist's PC through LAN and each assessment process of subjects are displayed onto audiometrist's monitor in real time. And if necessary, it makes possible for audometrist to adjust the assessment progress of particular subject like as a face to face model.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.38 no.2
• /
• pp.33-41
• /
• 2001

Currently, the compression is one of the most important technology in multimedia society. Audio files arc rapidly propagated throughout internet Among them, the most famous one is MP-3(MPEC-1 Laver3) which can obtain CD tone from 128Kbps, but tone quality is abruptly down below 64Kbps. MPEC-II AAC(Advanccd Audio Coding) is not compatible with MPEG 1, but it has high compression of 1.4 times than MP 3, has max. 7.1 and 96KHz sampling rate. In this paper, we propose an algorithm that decreased the capacity of AAC encoding computation but increased the processing speed by optimizing psychoacoustic model which has enormous amount of computation in MPEG 2 AAC encoder. The optimized psychoacoustic model algorithm was implemented by C++ language. The experiment shows that the psychoacoustic model carries out FFT(Fast Fourier Transform) computation of 3048 point with 44.1 KHz sampling rate for SMR(Signal to Masking Ratio), and each entropy value is inputted to the subband filters for the control of encoder block. The proposed psychoacoustic model is operated with high speed because of optimization of unpredictable value. Also, when we transform unpredictable value into a tonality index, the speed of operation process is increased by a tonality index optimized in high frequency range.

• The Journal of the Acoustical Society of Korea
• /
• v.24 no.6
• /
• pp.353-357
• /
• 2005

Declining auditory performance with advanced age is a well known and common problem that is becoming more Prevalent due to the increasing number of elderly people in our society. We introduce a novel ARCISM (Audiogram Result Computer Input. Save & Management software) data management program which enables the assessment of the risk of past history of hearing impairment on the basis of known risk factors. This study investigates the reference levels of pure tone hearing threshold of normal aging in Korean and the difference between fenders. The subjects were carefully selected by questionnaire and absence of any history of otologic infection, noise exposure. and ototoxic drug among 1603 subjects. who visited Health Promotion Center in Daegu Fatima Hospital for one year. The results show (1) hearing sensitivity declines with age. (2) higher frequency shows steeper slope of hearing declines than lower frequency. and (3) there were more hearing loss at 4 and 8 kHz in men than in women. Due to the ARCISM program. it was possible to manage huge data of hearing results and to obtain the reference level of a9e-related hearing declines. Furthermore, we expect that the results of this study can be the fundamental data for hearing rehabilitation for the elderly and for developing suitable hearing aids for Korean.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.45 no.5
• /
• pp.13-20
• /
• 2008

Although digital hearing aid algorithms have been developed to compensate hearing loss and to help hearing impaired people to communicate with others, digital hearing aid user still complain about difficulty of hearing the speech. The reason could be the quality of speech through digital hearing aid is insufficient to understand the speech caused by feedback, residual noise and etc. And another thing is masking effect among formants that makes sound quality low. In this study, we measured the masking characteristics of normal listeners and hearing impaired listeners having presbyacusis to confirm masking effect in speech itself. The experiment is composed of 5 tests; pure tone test, speech reception threshold (SRT) test, word recognition score (WRS) test, puretone masking test and speech masking test. In speech masking test, there are 25 speeches in each speech set. And log likelihood ratio (LLR) is introduced to evaluate the distortion of each speech objectively. As a result, the speech perception became lower by increasing the quantity of formant enhancement. And each enhanced speech in a speech set has statistically similar LLR, however speech perception is not. It means that acoustic masking effect rather than distortion influences speech perception. In actuality, according to the result of frequency analysis of the speech that people can not answer correctly, level difference between first formant and second formant is about 35dB, and it is similar to result of pure tone masking test(normal hearing subject:36.36dB, hearing impaired subject:32.86dB). Characteristics of masking effect is not similar between normal listeners and hearing impaired listeners. So it is required to check the characteristics of masking effect before wearing a hearing aid and to apply this characteristics to fitting.