The relationship between sentence intelligibility, band importance, and signal covariance

The present study investigates the relationship between sentence intelligibility, band importance, and patterns of spectro-temporal covariation between frequency bands. Sixteen listeners transcribed sentences acoustically degraded to 5, 8, or 15 frequency bands. Half of the sentences retained the frequency bands that captured more signal covariance. The other half retained the bands accounting for less signal covariance. Sentence intelligibility was significantly higher in the high-covariance condition. Critically, this finding was predicted by differences in band importance across reconstructed sentences. These findings provide a mechanistic relationship between the contributions of signal covariance and band importance to sentence intelligibility.