Effect of spectrally and temporally altered auditory feedback on the speech of hard of hearing persons

Abstract

Nine participants with severe to profound hearing loss read a six‐sentence passage under different auditory feedback conditions that included spectrally altered and/or delayed speech. Spectral smearing was implemented by filtering the speech signal into either one, two, or four frequency bands, extracting respective amplitude envelope(s), and amplitude‐modulating the corresponding noise band(s). As the number of the filter bands decreased, the spectral information, and therefore the intelligibility of the resulting noise replicas of the speech signal, diminished. The three noise conditions and the unaltered speech were each tested under the simultaneous and four delayed (25, 50, 100, and 200 ms) feedback conditions. Auditory feedback was presented via insert earphones at the participant’s most comfortable listening level. Different measures of duration, intensity, and fundamental frequency (f0) were computed on individual sentences, and subjected to statistical analyses. Results indicate a differential effect of the two feedback manipulations on different acoustic parameters. Although speech delays affected duration and intensity measures the most, spectral smearing showed the most robust effect on f0 variability. Individual differences were significant. Auditory self‐monitoring will be discussed as a function of hearing loss.