The present study investigated the role and relative contribution of envelope and temporal fine structure (TFS) to sentence recognition in noise. Target and masker stimuli were added at five different signal-to-noise ratios (SNRs) and filtered into 30 contiguous frequency bands. The envelope and TFS were extracted from each band by Hilbert decomposition. The final stimuli consisted of the envelope of the target/masker sound mixture at x dB SNR and the TFS of the same sound mixture at y dB SNR. A first experiment showed a very limited contribution of TFS cues, indicating that sentence recognition in noise relies almost exclusively on temporal envelope cues. A second experiment showed that replacing the carrier of a sound mixture with noise (vocoder processing) cannot be considered equivalent to disrupting the TFS of the target signal by adding a background noise. Accordingly, a re-evaluation of the vocoder approach as a model to further understand the role of TFS cues in noisy situations may be necessary. Overall, these data are consistent with the view that speech information is primarily extracted from the envelope while TFS cues are primarily used to detect glimpses of the target.

Band-importance functions created using the compound method [Apoux and Healy (2012). J. Acoust. Soc. Am. 132, 1078-1087] provide more detail than those generated using the ANSI technique, necessitating and allowing a re-examination of the influences of speech material and talker on the shape of the band-importance function. More specifically, the detailed functions may reflect, to a larger extent, acoustic idiosyncrasies of the individual talker's voice. Twenty-one band functions were created using standard speech materials and recordings by different talkers. The band-importance functions representing the same speech-material type produced by different talkers were found to be more similar to one another than functions representing the same talker producing different speech-material types. Thus, the primary finding was the relative strength of a speech-material effect and weakness of a talker effect. This speech-material effect extended to other materials in the same broad class (different sentence corpora) despite considerable differences in the specific materials. Characteristics of individual talkers' voices were not readily apparent in the functions, and the talker effect was restricted to more global aspects of talker (i.e., gender). Finally, the use of multiple talkers diminished any residual effect of the talker.

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In accord with psychoacoustic data, young children do not appear to focus on a spectral region of interest and ignore other regions during speech recognition. This tendency may help account for their typically poorer speech perception in noise. This study also appears to capture an important developmental stage, during which a substantial refinement in spectral listening occurs.

The relative independence of time-unit processing during speech reception was examined. It was found that temporally interpolated noise, even at very high levels, had little effect on sentence recognition using masking-release conditions similar to those of Kwon et al. [(2012). J. Acoust. Soc. Am. 131, 3111À3119]. The current data confirm the earlier conclusions of Kwon et al. involving masking release based on the relative timing of speech and noise. These data also indicate substantial levels of independence in the time domain, which has implications for current theories of speech perception in noise.