Volume 134, Issue 3, September 2013
Index of content:
- SPEECH PERCEPTION 
134(2013); http://dx.doi.org/10.1121/1.4816409View Description Hide Description
Masking release (MR) is the improvement in speech intelligibility for a fluctuating interferer compared to stationary noise. Reduction in MR due to vocoder processing is usually linked to distortions in the temporal fine structure of the stimuli and a corresponding reduction in the fundamental frequency (F0) cues. However, it is unclear if envelope periodicity related to F0, produced by the interaction between unresolved harmonics, contributes to MR. In the present study, MR was determined from speech reception thresholds measured in the presence of stationary speech-shaped noise and a competing talker. Two types of processing were applied to the stimuli: (1) An amplitude- and frequency-modulated vocoder attenuated the envelope periodicity and (2) high-pass (HP) filtering (cutoff = 500 Hz) reduced the influence of F0-related information from low-order resolved harmonics. When applied individually, MR was unaffected by HP filtering, but slightly reduced when envelope periodicity was attenuated. When both were applied, MR was strongly reduced. Thus, the results indicate that F0-related information is crucial for MR, but that it is less important whether the F0-related information is conveyed by low-order resolved harmonics or by envelope periodicity as a result of unresolved harmonics. Further, envelope periodicity contributes substantially to MR.
Role and relative contribution of temporal envelope and fine structure cues in sentence recognition by normal-hearing listeners134(2013); http://dx.doi.org/10.1121/1.4816413View Description Hide Description
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.
Auditory enhancement and second language experience in Spanish and English weighting of secondary voicing cues134(2013); http://dx.doi.org/10.1121/1.4817845View Description Hide Description
The role of secondary cues in voicing categorization was investigated in three listener groups: Monolingual English (n = 20) and Spanish speakers (n = 20), and Spanish speakers with significant English experience (n = 16). Results showed that, in all three groups, participants used onset f0 in making voicing decisions only in the positive voice onset time (VOT) range (short lag and long lag tokens), while there was no effect of onset f0 on voicing categorization within the negative VOT range (voicing lead tokens) for any of the participant groups. These results support an auditory enhancement view of perceptual cue weighting: Onset f0 serves as a secondary cue to voicing only in the positive VOT range where it is not overshadowed by the presence of pre-voicing. Moreover, results showed that Spanish learners of English gave a significantly greater weight to onset f0 in their voicing decisions than did listeners in either of the other two groups. This result supports the view that learners may overweight secondary cues to distinguish between non-native categories that are assimilated to the same native category on the basis of a primary cue.
134(2013); http://dx.doi.org/10.1121/1.4817926View Description Hide Description
This study examined how semantically related information facilitates the intelligibility of spoken sentences in the presence of masking sound, and how this facilitation is influenced by masker type and by individual differences in cognitive functioning. Dutch sentences were masked by stationary noise, fluctuating noise, or an interfering talker. Each sentence was preceded by a text cue; cues were either three words that were semantically related to the sentence or three unpronounceable nonwords. Speech reception thresholds were adaptively measured. Additional measures included working memory capacity (reading span and size comparison span), linguistic closure ability (text reception threshold), and delayed sentence recognition. Word cues facilitated speech perception in noise similarly for all masker types. Cue benefit was related to reading span performance when the masker was interfering speech, but not when other maskers were used, and it did not correlate with text reception threshold or size comparison span. Better reading span performance was furthermore associated with enhanced delayed recognition of sentences preceded by word relative to nonword cues, across masker types. The results suggest that working memory capacity is associated with release from informational masking by semantically related information, and additionally with the encoding, storage, or retrieval of speech content in memory.