Infinite peak clipping as a means of amplitude compression

Abstract

Infinite peak clipping is a simple and effective technique for transmitting speech over an analog channel with limited dynamic range. However, the technique has yet to be applied seriously to the problem of limited auditory dynamic range accompanying sensorineural hearing loss. In this project we have begun assessing infinite clipping as a means of amplitude compression by determining: (1) the compression of the range of speech levels when clipping is followed by post-filtering (as is presumed to occur when clipped speech is analyzed by the ear); and (2) the spectral distortions due to clipping and how these can be minimized by prefiltering. We have found that the (10%–90%) widths of level distributions of clipped-and-filtered speech are about 10–15 dB and relatively independent of the characteristics of the post-filter. Detrimental distortions of speech spectra can be reduced by isolating the formant regions with filters before and after the clippers. Intelligibility results with preliminary clipping-based systems will be described. [Work supported by NIH.]