Intelligibility for Binaural Speech with Discarded Low-SNR Speech Components

Abstract

Speech intelligibility in multitalker settings improves when the target speaker is spatially separated from the interfering speakers. A factor that may contribute to this improvement is the improved detectability of target-speech components due to binaural interaction in analogy to the Binaural Masking Level Difference (BMLD). This would allow listeners to hear target speech components within specific time-frequency intervals that have a negative SNR, similar to the improvement in the detectability of a tone in noise when these contain disparate interaural difference cues. To investigate whether these negative-SNR target-speech components indeed contribute to speech intelligibility, a stimulus manipulation was performed where all target components were removed when local SNRs were smaller than a certain criterion value. It can be expected that for sufficiently high criterion values target speech components will be removed that do contribute to speech intelligibility. For spatially separated speakers, assuming that a BMLD-like detection advantage contributes to intelligibility, degradation in intelligibility is expected already at criterion values below 0 dB SNR. However, for collocated speakers it is expected that higher criterion values can be applied without impairing speech intelligibility. Results show that degradation of intelligibility for separated speakers is only seen for criterion values of 0 dB and above, indicating a negligible contribution of a BMLD-like detection advantage in multitalker settings. These results show that the spatial benefit is related to a spatial separation of speech components at positive local SNRs rather than to a BMLD-like detection improvement for speech components at negative local SNRs.

Contribution of binaural masking release to improved speech intelligibility for different masker types

“…However, in the speech‐in‐speech condition, the difference in masking release between HRTF and ISE condition is small. This is consistent with the findings by Schoenmaker and Van De Par (). There are two possible reasons for this significant difference that were further investigated.…”

“…According to Cooke (), a suitable criterion for considering a spectrotemporal unit as a glimpse lies in the range of −2 to −5 dB. A similar suggestion is made by Schoenmaker and Van De Par (). Their experiment showed that removing speech fragments up to a local SNR of −4 dB did not have a significant effect on the speech intelligibility.…”

Sparse periodicity‐based auditory features explain human performance in a spatial multitalker auditory scene analysis task

“…To further investigate this question, this study tested the hypothesis that low signal‐to‐noise ratio target components do not contribute significantly to speech discrimination in a spatial multitalker condition. For this, we apply an auditory “glimpsing” model (Josupeit & Hohmann, ) to a speech intelligibility task within a multitalker scene with a manipulated target stimulus (Schoenmaker & van de Par, ).…”

“…Several studies indicate that listeners mainly process “glimpses” of information to decode complex auditory scenes (Best et al ., ; Cooke, ; Josupeit & Hohmann, ; Schoenmaker & van de Par, ). Glimpses are defined as spectro‐temporal undisrupted pieces of information (Darwin, ), that is a glimpse contains the information from exactly one sound source.…”

“…A psychoacoustic study by Schoenmaker and van de Par () provided evidence that listeners mainly use glimpses to understand a target talker masked by two interfering talkers. In this study, the target signal was manipulated, such that all time‐frequency units of which the signal‐to‐noise ratio (SNR) fell below a certain value, termed SNR crit , were eliminated from the signal.…”