Role and relative contribution of temporal envelope and fine structure cues in sentence recognition by normal-hearing listeners

Abstract

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.

Physiology, Psychoacoustics and Cognition in Normal and Impaired Hearing

“…Previous studies have demonstrated that E is sufficient for speech perception Apoux et al 2013), while FS is important for pitch perception and lexical tone perception (Xu and Pfingst 2003). Mandarin Chinese is a tone language with four phonologically distinctive tones that are characterized by syllable-level fundamental frequency (F0) contour patterns.…”

Level considerations for chimeric processing: Temporal envelope and fine structure contributions to speech intelligibility

“…In such conditions, it has been proposed that the frequency-modulated carrier of the signal, the acoustic temporal fine structure (TFS), may provide additional information for speech intelligibility by facilitating the glimpsing of spectro-temporal moments at favorable signal-to-noise ratios (SNR), that is, by listening in the amplitude dips of the interfering masker (Lorenzi et al, 2006;Hopkins and Moore, 2009). Recent investigations have suggested that the availability of the speech TFS during these moments of favorable SNRs may be particularly important for source segregation (Apoux et al, 2013). TFS may also be important in some intelligibility metrics (Chen et al, 2013) and play an important role in the integration of speech fragments (Gilbert and Lorenzi, 2010;Gnansia et al, 2010).…”

“…Recently, Apoux et al (2013) presented a very instructive framework for viewing the role and contribution of the TFS to speech intelligibility, particularly in marrying the findings of previous vocoder-and chimeric-based signal processing strategies. Vocoderbased methods extract the ENV through rectification and low-pass filtering and then modulate an independent noise carrier.…”

“…Vocoderbased methods extract the ENV through rectification and low-pass filtering and then modulate an independent noise carrier. However, the noise carrier is typically used for both noise vocoding the target as well as for masking, resulting in a sound segregation problem independent of the listener's ability to process TFS cues (Apoux et al, 2013). Chimeric-based methods use the Hilbert transform to extract ENV and TFS components from clean (i.e., quiet) and noisy samples of the same speech signal.…”

The Relative Contributions of Temporal Envelope and Fine Structure to Mandarin Lexical Tone Perception in Auditory Neuropathy Spectrum Disorder

“…Previous studies have demonstrated that E is sufficient for speech perception (Shannon et al 1995;Apoux et al 2013), while FS is important for pitch perception (Smith et al 2002) and lexical tone perception (Xu and Pfingst 2003). Mandarin Chinese is a tone language with four phonologically distinctive tones that are characterized by syllable-level fundamental frequency (F0) contour patterns.…”