Revisiting perceptual compensation for effects of reverberation in speech identification.

Listeners were given the task to identify the stop-consonant [t] in the test-word "stir" when the word was embedded in a carrier sentence. Reverberation was added to the test-word, but not to the carrier, and the ability to identify the [t] decreased because the amplitude modulations associated with the [t] were smeared. When a similar amount of reverberation was also added to the carrier sentence, the listeners' ability to identify the stop-consonant was restored. This phenomenon has in previous research been considered as evidence for an extrinsic compensation mechanism for reverberation in the human auditory system [Watkins (2005). J. Acoust. Soc. Am. 118, 249-262]. In the present study, the reverberant test-word was embedded in additional non-reverberant carriers, such as white noise, speech-shaped noise and amplitude modulated noise. In addition, a reference condition was included where the test-word was presented in isolation, i.e., without any carrier stimulus. In all of these conditions, the ability to identify the stop-consonant [t] was enhanced relative to the condition using the non-reverberant speech carrier. The results suggest that the non-reverberant speech carrier produces an interference effect that impedes the identification of the stop-consonant. These findings raise doubts about the existence of the compensation mechanism.