The acoustic and perceptual effects of two noise-suppression algorithms.
Internal noise generated by hearing-aid circuits can be audible and objectionable to aid users, and may lead to the rejection of hearing aids. Two expansion algorithms were developed to suppress internal noise below a threshold level. The multiple-channel algorithm's expansion thresholds followed the 55-dB SPL long-term average speech spectrum, while the single-channel algorithm suppressed sounds below 45 dBA. With the recommended settings in static conditions, the single-channel algorithm provided lower noise levels, which were perceived as quieter by most normal-hearing participants. However, in dynamic conditions "pumping" noises were more noticeable with the single-channel algorithm. For impaired-hearing listeners fitted with the ADRO amplification strategy, both algorithms maintained speech understanding for words in sentences presented at 55 dB SPL in quiet (99.3% correct). Mean sentence reception thresholds in quiet were 39.4, 40.7, and 41.8 dB SPL without noise suppression, and with the single- and multiple-channel algorithms, respectively. The increase in the sentence reception threshold was statistically significant for the multiple-channel algorithm, but not the single-channel algorithm. Thus, both algorithms suppressed noise without affecting the intelligibility of speech presented at 55 dB SPL, with the single-channel algorithm providing marginally greater noise suppression in static conditions, and the multiple-channel algorithm avoiding pumping noises.
Zakis
Justin A
JA
Dynamic Hearing Pty Ltd, 2 Chapel Street, Richmond, Victoria 3121, Australia. jzakis@dynamichearing.com.au
Wise
Christi
C
D000465:Algorithms; D001309:Auditory Threshold; D003638:Deafness / Q000628:therapy*; D006309:Hearing; D006310:Hearing Aids; D006801:Humans; D009622:Noise / Q000517:prevention & control*; D013061:Speech Acoustics; D013065:Speech Intelligibility; D013067:Speech Perception