Uncomodulated glimpsing in "checkerboard" noise.
The ability of listeners to "glimpse" acoustic cues during the quieter sections of an interrupted noise has primarily been studied using maskers with interruptions occurring simultaneously across the entire frequency range of the masker--broadband comodulated interruptions. Here, the possibility of uncomodulated glimpsing (the glimpsing of acoustic cues separated both in time and frequency) was investigated. To achieve this, speech reception thresholds for a set of intervocalic consonants were adaptively measured in 100-Hz to 10-kHz pink noise divided into a varying number of frequency bands of equal energy. In uncomodulated noise conditions, the odd and even numbered bands were switched on and off alternately at a rate of 10 Hz. The spectrograms of such noises (on log frequency scales), resemble portions of a checkerboard. Glimpsing in "checkerboard" noise was found with maskers divided into two and four bands, but not into eight bands or more. Further investigations showed that, in the two-band case, this release from masking was indeed due to uncomodulated glimpsing, and not simply attributable to glimpsing in one of the modulated bands. In the four-band case, the release from masking in checkerboard noise can be accounted for without recourse to uncomodulated glimpsing. Interestingly, conditions which allowed glimpsing resulted in greater intersubject variability. The implications of these results for quantitative analyses of masker fluctuations are discussed.
Howard-Jones
P A
PA
Department of Phonetics and Linguistics, University College London, England.
Rosen
S
S
D000161:Acoustic Stimulation; D001309:Auditory Threshold; D005260:Female; D006801:Humans; D008297:Male; D009622:Noise; D013061:Speech Acoustics; D013067:Speech Perception