Selective spatial attention modulates bottom-up informational masking of speech.
To hear out a conversation against other talkers listeners overcome energetic and informational masking. Largely attributed to top-down processes, information masking has also been demonstrated using unintelligible speech and amplitude-modulated maskers suggesting bottom-up processes. We examined the role of speech-like amplitude modulations in information masking using a spatial masking release paradigm. Separating a target talker from two masker talkers produced a 20 dB improvement in speech reception threshold; 40% of which was attributed to a release from informational masking. When across frequency temporal modulations in the masker talkers are decorrelated the speech is unintelligible, although the within frequency modulation characteristics remains identical. Used as a masker as above, the information masking accounted for 37% of the spatial unmasking seen with this masker. This unintelligible and highly differentiable masker is unlikely to involve top-down processes. These data provides strong evidence of bottom-up masking involving speech-like, within-frequency modulations and that this, presumably low level process, can be modulated by selective spatial attention.
School of Medical Sciences and The Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia.
Simon
S
Carlile
School of Medical Sciences, University of Sydney, Sydney, NSW 2006 Australia.
Caitlin
C
Corkhill
D000161:Acoustic Stimulation; D000328:Adult; D001288:Attention / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology; D001309:Auditory Threshold / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D010470:Perceptual Masking / Q000502:physiology*; D013060:Speech / Q000502:physiology*; D055815:Young Adult