The Effects of Spectral Smearing on Hebrew Phoneme and Word Recognition

The purpose of this study was to examine the effect of loss of spectral detail on speech perception in Hebrew. Spectral smearing was carried out by multiplying the speech signal by a series of low-passed white noise samples, causing tonal components in the signal to be replaced by noise. Smearing bandwidths of 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz, 8000Hz and full bandwidth were used. Smearing was applied to 15 isophonemic lists, each with 10 one-syllable CVC Hebrew words. Results of eight normal-hearing subjects show that a (1) smearing bandwidth of approximately 1000Hz and 2000Hz reduced word and phoneme recognition to 50%, respectively, and (2) vowels were more susceptible to the effects of spectral smearing than consonants. These results are similar to the results reported in English and can be explained by the relative importance of spectral and temporal cues for the perception of speech.