Band importance for speech-in-speech recognition in the presence of extended high-frequency cues

Abstract

Extended high-frequency (EHF; 8–20 kHz) cues support speech recognition in noisy backgrounds, particularly when the masker has reduced EHF levels relative to the target. This scenario can occur in natural auditory scenes when the target talker is facing the listener, but the masker talkers are not. The EHF benefit stands in contrast to past studies that have focused on lower frequencies and presumed that EHFs play no role in speech intelligibility. Although EHF cues improve speech recognition, it is unclear how the magnitude of benefit compares to that of other portions of the speech spectrum. In this ongoing study, we measure band importance functions (BIFs) for a female target and two-talker masker by notch filtering individual contiguous bands from 40 to 20 000 Hz. With the target facing the listener, two masking conditions were tested: (1) masker facing the listener; (2) masker facing 56.25°. Preliminary data indicate an interaction between the filtered band and masker head orientation. For the facing condition, the BIF shows a peak between 0.4 and 3 kHz and drops sharply at higher frequencies, resembling previous data. When the masker faces away, however, the benefit of EHFs increases relative to the lower bands, somewhat flattening the BIF. [Work supported by NIH grant R01-DC019745].