• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.779-784
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• 2020

In this paper, we improved the high frequency noise characteristics of the previously proposed hearing aid circuits for presbycusis, and we designed and fabricated a stereo hearing aid module. The cause of high frequency noise, which occurs in some cases in the previous circuits under high gain conditions, was analyzed through simulations. Two mute switches were added to adjust each boosting gain for right and left ears more accurately by muting the sound of the other ear when adjusting the gain of one ear in the stereo hearing aid module.

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

• Journal of rehabilitation welfare engineering & assistive technology
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• v.11 no.3
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• pp.215-221
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• 2017

Audiological rehabilitation by itself can provide satisfactory services through acquisition of background information on hearing loss, audiological evaluation, analysis of electroacoustic characteristics of hearing aids, and determining acoustic gain. However, hearing can be exacerbated, and sound pressure level of hearing aids can be lowered. Moreover, breakdown of hearing aids can happen. Therefore, the early detection of hearing loss and regular follow-up observations are very important. The aim of this study concern the direction of effective audiological rehabilitation by checking the clinical cases where hearing aids fitting failures were found.

• Journal of Audiology & Otology
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• v.25 no.2
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• pp.72-79
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• 2021

Background and Objectives: The speech-in-noise test is typically performed using an audiometer. The results of the digit-in-noise recognition (DIN) test may be influenced by the flat frequency response of free-field audiometry and frequency of the hearing aid fit based on fitting rationale. This study aims to investigate the DIN test in unaided and aided conditions. Subjects and Methods: Thirty four adults with moderate and severe sensorineural hearing loss (SNHL) participated in the study. The signal-to-noise ratio (SNR) for 50% of the DIN test was obtained in the following two conditions: 1) the unaided condition, performed using an audiometer in a free field; and 2) aided condition, performed using a hearing aid with an unvented individual earmold that was fitted based on NAL-NL2. Results: There was a statistically significant elevation in the mean SNR for the severe SNHL group in both test conditions when compared with that of the moderate SNHL group. In both groups, the SNR for the aided condition was significantly lower than that of the unaided condition. Conclusions: Speech recognition in hearing-impaired patients can be realized by fitting hearing aids based on evidence-based fitting rationale rather than by measuring it using free-field audiometry measurement that is utilized in a routine clinic setup.

• Journal of Audiology & Otology
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• v.25 no.1
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• pp.8-13
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• 2021

Background and Objectives: In 2013, the Singapore government reviewed and expanded the Senior Mobility Fund (SMF) to provide subsidy for assistive devices, including hearing aids (HA). While SMF has improved accessibility to HA, its impact on HA acquisition has not been determined. The study aims to elucidate the influence of SMF on HA acquisition and the relationship between financial funding and compliance to HA use. Subjects and Methods: Retrospective review of 643 patients seen between January 2017 to January 2018 at the earnose and throat specialist outpatient clinic, who were referred for a hearing aid evaluation. Of the 643 patients, 109 patients with baseline hearing handicap (HH) scores recorded, and no formal diagnosis of cognitive impairment were included. The patients were grouped according to SMF eligibility and clinical data were obtained. Results: The odds ratio for acquiring HA was significantly higher with SMF, regardless of HH scores. When looking at actual degree of hearing loss (DHL), HA uptake was significantly higher in the least severe of DHL categories. There is no relationship between SMF and compliance to HA use. However, HH score is positively correlated with data log in regression analyses. Conclusions: SMF appears to influence HA acquisition. Especially in financially funded patients with low self-perceived HH, the benefits of HA may be underappreciated given the few hours of HA use. Further studies are warranted to investigate the impact of financial funding on outcomes of HA users to help policy planners and clinicians be prudent in the utilization of SMF.

• Korean Journal of Audiology
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• v.25 no.1
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• pp.8-13
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• 2021

Background and Objectives: In 2013, the Singapore government reviewed and expanded the Senior Mobility Fund (SMF) to provide subsidy for assistive devices, including hearing aids (HA). While SMF has improved accessibility to HA, its impact on HA acquisition has not been determined. The study aims to elucidate the influence of SMF on HA acquisition and the relationship between financial funding and compliance to HA use. Subjects and Methods: Retrospective review of 643 patients seen between January 2017 to January 2018 at the earnose and throat specialist outpatient clinic, who were referred for a hearing aid evaluation. Of the 643 patients, 109 patients with baseline hearing handicap (HH) scores recorded, and no formal diagnosis of cognitive impairment were included. The patients were grouped according to SMF eligibility and clinical data were obtained. Results: The odds ratio for acquiring HA was significantly higher with SMF, regardless of HH scores. When looking at actual degree of hearing loss (DHL), HA uptake was significantly higher in the least severe of DHL categories. There is no relationship between SMF and compliance to HA use. However, HH score is positively correlated with data log in regression analyses. Conclusions: SMF appears to influence HA acquisition. Especially in financially funded patients with low self-perceived HH, the benefits of HA may be underappreciated given the few hours of HA use. Further studies are warranted to investigate the impact of financial funding on outcomes of HA users to help policy planners and clinicians be prudent in the utilization of SMF.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.231-234
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• 2002

In this paper, we propose an efficient bias circuit for hearing aid using discrete BJT. The collector feedback bias circuit, widely used for the hearing aid, has a resister for negative feedback. As the resistor affects AC and DC simultaneously, it is quite difficult to adjust amplifier gain without changing DC bias point. The previous bias circuit also has weak point to be oscillated by the positive feedback of power noise if gain of hearing aid is high. In the proposed circuit, we can reduce the two weak points of the previous circuit by adding a resistor which is ${\beta}$ times larger than collector resistor between base of BJT and power supply.

• The Journal of the Acoustical Society of Korea
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• v.24 no.2E
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• pp.38-45
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• 2005

The noise reduction of the In-The-Ear (ITE) hearing aid (HA) can be achieved by arrays of microphones. Each of the right and the left ears was assumed to have two HA microphones. These arrays of HA microphones produce particular patterns of directivity by some time delay between two microphones. The directivity pattern geometrically increase the S/N ratio. The boundary element method (BEM) was used for the three dimensional simulation of the HA directivity pattern with the two pairs' microphone arrays. The separation between two microphones was fixed to 10 mm. The time delay between the two microphones was calculated to produce the most narrow directivity pattern in the fore front of the head. The variation of the time delay was examined in accordance with input frequencies. This numerical analysis may be then applied for the calculation of the time delay parameter of the digital hearing aid DSP chip.

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.272-279
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• 2016

In this paper, the realization of a hearing aid adaptively cancelling feedback noise was considered. Conventional least mean square method in time domain was transformed into frequency domain in order to minimize computational burden. The adaptive filter algorithm was evaluated by Matlab (Matrix laboratory), and it was confirmed by CSR 8675 Bluetooth DSP IC (Digital Signal Processor Integrated Circuit) chip firmware realization. Some remote control features by a smart phone was added to the smart hearing aid for user interface easiness.

• The Journal of the Acoustical Society of Korea
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• v.34 no.2
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• pp.91-97
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• 2015

In this paper, wireless communication from a smart phone to a hearing aid using audible frequency band sound was considered. 1kHz single channel carrier frequency was applied for amplitude shift keying (ASK) binary data modulation, and the result of the transmission and reception was tested. The overall system process was precisely explained and experimentally evaluated. The result will be applied for realizing a digital hearing aid with remote control feature by a smart phone.