| In natural environments, the auditory system continuously has tosolve the problem of segregating sounds that convey relevantinformation from the confounding mixture of background noise. Earlierpsychophysical studies have shown that the processes underlyingfigure-ground segregation in complex 'auditory scenes' are highlyefficient. This capacity is exemplified by the 'auditory continuityillusion', in which an acoustic target, masked momentarily bybroad-band noise, is perceived as continuing through the noise, evenwhen the target is physically turned off. So far, however, detailed knowledge about the neural mechanismsunderlying auditory scene analysis is lacking. It has recently beenproposed that the primary auditory cortex may be the first stagebeyond the mere representation of a signal?s acoustics to subservethe formation of an ?auditory object?. In this project we test thishypothesis by identifying the neural substrates of auditory objectsegregation in the human brain by fMRI and, in parallel, byperforming single-unit recordings from primary and secondary areas ofauditory cortex in behaving monkeys. We will exploit parametricvariations of the continuity illusion and of relatedauditory-streaming paradigms (Bregman, 'Auditory Scene Analysis',1990). Monkeys and humans will be subjected to the same paradigms,to allow for a direct comparison. We expect that this combined effort will yield novel results andimportant insights into the neural mechanisms that underlie auditoryperception. Results will have considerable practical relevance, sincethey will be instrumental in improving the design of hearing aids and |
