The purpose of the present study was to investigate whether function of compression threshold (CT) affects the scores of Korean consonant perception test (KCPT) and sound quality in quiet and noisy environments. Methods: The subjects were 18 adults with sensorineural hearing loss, average age of 56.8 years, word recognition more than 40% and pure tone average of 54.3 dB HL. The hearing aids used in this study were behind-the-ear type hearing aid with more than 4 channels. After randomly adjusting the CT to 55, 65, 75 dB SPL in quiet and white noise environments (+6 dB signal-to-noise ratio), the scores of KCPT and preferences (clarity, sound quality, and loudness of noise) were evaluated. Results: The CT of 55 dB SPL and 65 dB SPL scored higher KCPT than CT of 65 dB SPL in noisy environment. In quiet environment, however, there was no difference in Korean consonant recognition score based on its CT. In the preferences assessment, CT of 55 dB SPL showed greater loudness of noise than CT of 75 dB SPL. However, the clarity and sound quality did not vary on CT in quiet and noisy environments. Conclusion: Based on the results of this study, it has been confirmed that CT may affect the recognition of Korean speech sounds and the loudness of noise. Therefore, the control of CT should be considered when adjusting electroacoustic elements of the multi-channel hearing aid.

Purpose: To compare the occlusion effect (OE) of a completely-in-the-canal (CIC) hearing aid and receiver-in-canal (RIC) hearing aid with open ear tip (OET), closed ear tip (CET), and double ear tip (DET), the present study measured the real-ear insertion gain (REIG) and psychoacoustic differences. Methods: While seventeen adults with normal hearing wearing the dummy CIC hearing aid and three types of ear-tips for the RIC hearing aid, they vocalized the /ee [i]/ sound. The REIG and psychoacoustic differences were measured at each condition and compared in terms of decibel and degree of occlusion. Results: First, OET and CET types for the RIC hearing aids were more effective to reduce the OE than both DET type of RIC hearing aid and CIC hearing aid. Second, there was no difference between DET type of the RIC hearing aid and CIC hearing aid in terms of REIG and psychoacoustics. Third, the REIG of the DET with RIC hearing aid and CIC hearing aids was lower in the frequency band of around 3,000 Hz than the other types such as OET and CET. Conclusion: The current results support that the OET and CET types for RIC hearing aids effectively help reducing the OE. Regardless, the CIC hearing aid which has reduced gain in the high frequencies also can provide better speech perception and sound quality. In conclusion, when selecting an open fit or custom hearing aid, the hearing-impaired listeners are recommended while considering both degree, type, and configuration of hearing loss and technical aspects of hearing aid.

To determine the effective release time (RT) for listening to Korean sounds when wearing hearing aids, we evaluated Korean nonsense syllabic word recognition scores (NSRS) and the clarity of conversation sounds, the size of noise, and the overall preferences as a function of RT. Methods: Twenty adults and elderly people with mild to severe sensorineural hearing loss were participated as subjects. In the quiet and noise environment, NSRS and preferences were evaluated after setting the RT of the multi-channel hearing aids to 70, 200, and 600 ms. Presentation level of nonsense syllabic word was 45 dB HL and signal-to-noise ratio was 6 dB in noise environment. Results: NSRS was not different as a function of RT in quiet, but NSRS of 200 ms was higher than 70 ms and 600 ms in noise environment. However, clarity, loudness of noise, and overall preference did not show a difference in RT in a quiet and noisy environment. Conclusion: Through this study, it was confirmed that Korean NSRS can be affected by RT. Therefore, in order to develop a hearing aid fitting formula that is effective in recognition of Korean speech sound, it is necessary to consider the RT.

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