Speech detection in spatial and nonspatial speech maskers

Abstract

The effect of perceived spatial differences on masking release was examined using a 4AFC speech detection paradigm. Targets were 20 words produced by a female talker. Maskers were recordings of continuous streams of nonsense sentences spoken by two female talkers and mixed into each of two channels ͑two talker, and the same masker time reversed͒. Two masker spatial conditions were employed: "RF" with a 4 ms time lead to the loudspeaker 60°horizontally to the right, and "FR" with the time lead to the front ͑0°͒ loudspeaker. The reference nonspatial "F" masker was presented from the front loudspeaker only. Target presentation was always from the front loudspeaker. In Experiment 1, target detection threshold for both natural and time-reversed spatial maskers was 17-20 dB lower than that for the nonspatial masker, suggesting that significant release from informational masking occurs with spatial speech maskers regardless of masker understandability. In Experiment 2, the effectiveness of the FR and RF maskers was evaluated as the right loudspeaker output was attenuated until the two-source maskers were indistinguishable from the F masker, as measured independently in a discrimination task. Results indicated that spatial release from masking can be observed with barely noticeable target-masker spatial differences.

Localization in speech mixtures by listeners with hearing loss

“…Nevertheless, it is difficult to rule out the possibility that increased uncertainty about the presence of the target influenced the localization data in the HI listeners. This idea requires further investigation with a larger group of subjects; very few studies have measured speech detection in NH listeners (Grant and Seitz, 2000;Balakrishnan and Freyman, 2008) and we are not aware of any studies in listeners with hearing loss. Assuming that impaired detection was not the primary cause of differences in errors across groups, hearing loss appears to degrade speech localization in a multitalker mixture while having no effect on speech localization in quiet.…”

A cocktail party model of spatial release from masking by both noise and speech interferers

“…Spatial separation of masker(s) from the target is an effective way to counteract informational masking (Kidd et al, 1998;Freyman et al, 1999, Arbogast et al, 2002. As a result, when the target is speech, the magnitude of SRM with speech maskers can be quite large relative to noise maskers, particularly under conditions that lead to high informational masking such as when targets and maskers are spoken by talkers of the same gender or by the same talker Balakrishnan and Freyman, 2008). Thus, a model of SRM for both noise and speech maskers would have to be flexible enough to accommodate key differences between these types of maskers.…”

Spatial release from masking with noise-vocoded speech

“…It is quite reasonable to consider that the intelligibility of the masker ͑and certainly that of the target͒ might be more important in recognition than in detection. Balakrishnan and Freyman ͑2008͒ showed that time-reversing a two-talker masker had almost no effect on detection in unprocessed speech conditions, whereas Freyman et al ͑2001͒ showed that time-reversing a masker did improve recognition performance in the F-F condition. On the other hand, with both time-reversed maskers and foreign language maskers, a substantial spatial advantage in the F-RF condition remained.…”