Compression and noise reduction : effects of compression and noise reduction on Mandarin speech perception and personal preferences among Mandarin speaking hearing impaired adults

Abstract

Hearing aid (HA) compression and noise reduction (NR) algorithms are designed to enhance hearing. Compression and NR could interact with each other in the presence of noise. This study evaluated the effects of NR and compression (syllabic and dual compression) on Mandarin speech perception among Mandarin speaking hearing impaired adults. The objectives of this study were: (1) to examine the combined effects of compression (syllabic compression and dual compression) and strength of NR on Mandarin speech perception in Mandarin speakers using HA, (2) to observe the relationship between mid-frequencies hearing sensitivity and HA compression and NR settings on Mandarin speech perception in Mandarin speakers using HA, (3) to examine the relationship between speech intelligibility and personal preference, (4) to study the effect of previous HA compression on speech recognition, and (5) to study the effect of previous HA compression on personal preference. 31 Mandarin speaking adults aged 18 and above with bilateral mild to profound hearing loss were tested using Mandarin Hearing in Noise Test and paired comparison of personal preferences over different HA settings. Results showed dual compression and syllabic compression yielded no difference in speech perception in quiet. In general, dual compression provided better speech intelligibility and greater sound quality in noisy condition. Strength of NR did not affect overall speech perception in noise. Participants preferred dual compression for better sound quality regardless of previous type of compression used. Findings were discussed in terms of relationship between HA settings, speech perception and personal preferences. Clinical significance was discussed. Limitations and directions for future research were explored.