Changes of Consonant Recognition and Sound Quality as a Function of Compression Threshold on Multi-Channel Hearing Aids

Abstract

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.