Speech perception through various signal processings
Igor V. Nábĕlek, W. Scott Wood, Kazurani J. M. Koike · The Journal of the Acoustical Society of America · 1980
Modified rhyme test (MRT) and the City University of New York nonsense syllables test (CUNY) were recorded through various speech processings: (1) amplitude compression for a 10:1 compression ratio (CR) with attack and release times 10 and 90 ms, respectively; (2) amplitude compression plus two types of peak clippings (CLIP); (3) amplitude compression plus high-frequency emphasis (HFE) with different attack and release times; and (4) three-channel multiband compression (MBC) in which the CR in each channel was adjusted on the basis of the subject's dynamic range. The compression threshold was set 25 dB below the average maximum RMS level of the vowels of test items in the MRT or CUNY. The processed signal was amplified with individually adjusted frequency responses and delivered to the listeners via a circumaural earphone. The presentation of speech was always at the comfortable level for each individual listener. All the testings were done in quiet. The MRT mean scores in percent correct did not differ among test conditions. The CUNY mean scores in percent correct were 8% higher on the average for compression or compression plus CLIP, 8% lower on the average for compression plus HFE, and about the same for MBC in comparison to the reference score for no compression (CR = 1). The results of the statistical analysis will be presented. [Work supported by NIH NS 12946.]