Adaptation to spectrally-rotated speech

Abstract

Much recent interest surrounds listeners' abilities to adapt to various transformations that distort speech. An extreme example is spectral rotation, in which the spectrum of low-pass filtered speech is inverted around a center frequency (2 kHz here). Spectral shape and its dynamics are completely altered, rendering speech virtually unintelligible initially. However, intonation, rhythm, and contrasts in periodicity and aperiodicity are largely unaffected. Four normal hearing adults underwent 6 h of training with spectrally-rotated speech using Continuous Discourse Tracking. They and an untrained control group completed pre- and post-training speech perception tests, for which talkers differed from the training talker. Significantly improved recognition of spectrally-rotated sentences was observed for trained, but not untrained, participants. However, there were no significant improvements in the identification of medial vowels in /bVd/ syllables or intervocalic consonants. Additional tests were performed with speech materials manipulated so as to isolate the contribution of various speech features. These showed that preserving intonational contrasts did not contribute to the comprehension of spectrally-rotated speech after training, and suggested that improvements involved adaptation to altered spectral shape and dynamics, rather than just learning to focus on speech features relatively unaffected by the transformation.

Getting the Cocktail Party Started: Masking Effects in Speech Perception

“…It has a largely unchanged pitch profile, where some vowels remain relatively unchanged and some voice and manner cues are preserved. However, it is still unintelligible without significant training (Azadpour & Balaban, 2008; Blesser, 1972; Green, Rosen, Faulkner, & Paterson, 2013).…”

Feel the Noise: Relating Individual Differences in Auditory Imagery to the Structure and Function of Sensorimotor Systems

“…The acoustic signal was first equalized with a filter (essentially high-pass) that gave the rotated signal approximately the same long-term spectrum as the original. This equalizing filter (33-point finite impulse response [FIR]) was constructed based on measurements of the long-term average spectrum of speech ( Byrne et al 1994 ), although the roll-off below 120 Hz was ignored, and a flat spectrum below 420 Hz was assumed ( Scott, Rosen, et al 2009 ; Green et al 2013 ). The equalized signal was then amplitude modulated by a sinusoid at 4 kHz, followed by low-pass filtering at 3.8 kHz.…”

The effects of training length on the perceptual learning of time-compressed speech and its generalization

“…Support for this assumption comes from observations that even after years of experience with a second language, non-native speakers still have speech perception difficulties in adverse listening conditions (e.g., Conrad, 1989; and see Lecumberri et al, 2010, for review). Nevertheless, a prolonged learning phase has been documented in a small, but growing, number of training studies on distorted speech in which participants experienced many hundreds (and even thousands) of trials, sometimes across multiple training sessions (Stacey and Summerfield, 2008;Song et al, 2012;Green et al, 2013). The goal of the current study was therefore to explicitly test the hypothesis that longer training on a speech identification task can yield more learning and generalization than shorter-term training.…”