Redundancy of temporal envelope information across frequency bands in normal hearing individuals

Much research has focused on the role of different spectral aspects of the speech signal in speech perception. To date there had been little quantification of the temporal envelope of the speech signal for speech perception. The goal of this study was to examine the role of temporal envelope information in speech recognition by quantifying the shared temporal envelope information extracted from neighbouring high frequency 1/3-octave bands. The Envelope Difference Index (EDI) was used in the current study to calculate similarity of temporal envelope information between adjacent bands. There was significant shared information, but also novel information as well. In general, for listeners identifying nonsense words from limited temporal information, their speech recognition performance increased as the gap between two bands increased. Furthermore, the amount of shared information between 1/3 octave bands also decreased as a function of gap size. The acoustic measure of redundancy between pairs of bands did not predict intelligibility. Based on these results, models of speech intelligibility must account for this redundancy rather than assuming that bands can be analyzed and weighted individually.Medicine, Faculty ofAudiology and Speech Sciences, School ofGraduat