Spectral weights for localization and speech-in-speech recognition: Does phonemic content of speech targets matter?

A recent study from our lab showed that normal-hearing adults rely on cues in the region of 0.5-1 kHz for target talker localization and speech-in-speech recognition when the target can only be identified based on spatial cues. The present study evaluated whether similar weights are observed for speech-in-speech recognition that relies on access to vowels or consonants, given differences in the distributions of cues required for vowel and consonant recognition. Spectral weights were estimated by filtering stimuli into 1-octave-wide bands, dispersing those bands on the horizontal plane, and assessing the association between each band's position and participants' responses. Data were obtained for two tasks: 1) localization of the target relative to the masker (left vs. right), and 2) closed-set word recognition, where response alternatives differed either with respect to the initial consonant, vowel, or final consonant. As observed previously, weights for both tasks peaked at 0.5-1 kHz for all three stimulus sets. This result is consistent with the idea that the spatial cues supporting spatial release from masking are similar regardless of the frequency regions containing speech cues required for correct recognition of the target.