Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Effects of Instantaneous Multiband Dynamic Compression on Speech Intelligibility | EURASIP Journal on Applied Signal Processing 2005 18 3034-3043 2005 Hindawi Publishing Corporation Effects of Instantaneous Multiband Dynamic Compression on Speech Intelligibility Tobias Herzke Medizinische Physik Universitat Oldenburg D-26111 Oldenburg Germany Email Volker Hohmann Medizinische Physik Universitat Oldenburg D-26111 Oldenburg Germany Email Received 1 May 2004 Revised 26 January 2005 The recruitment phenomenon that is the reduced dynamic range between threshold and uncomfortable level is attributed to the loss of instantaneous dynamic compression on the basilar membrane. Despite this hearing aids commonly use slow-acting dynamic compression for its compensation because this was found to be the most successful strategy in terms of speech quality and intelligibility rehabilitation. Former attempts to use fast-acting compression gave ambiguous results raising the question as to whether auditory-based recruitment compensation by instantaneous compression is in principle applicable in hearing aids. This study thus investigates instantaneous multiband dynamic compression based on an auditory filterbank. Instantaneous envelope compression is performed in each frequency band of a gammatone filterbank which provides a combination of time and frequency resolution comparable to the normal healthy cochlea. The gain characteristics used for dynamic compression are deduced from categorical loudness scaling. In speech intelligibility tests the instantaneous dynamic compression scheme was compared against a linear amplification scheme which used the same filterbank for frequency analysis but employed constant gain factors that restored the sound level for medium perceived loudness in each frequency band. In subjective comparisons five of nine subjects preferred the linear amplification scheme and would not accept the instantaneous dynamic compression in hearing aids. Four of nine subjects did not perceive
