Auditory localization, detection of spatial separateness, and speech hearing in noise by hearing impaired listeners.

In two groups, one with sensorineural and the other with conductive-mixed hearing loss, measures were made of single-source localization and speech intelligibility in both spatially separate and nonseparate noise. There was also a test for detecting when two sounds came from the same location or from separate ones. Localization test results confirmed earlier findings, namely, disruption of vertical plane ability generally, and a further, particular disturbance to horizontal plane localization in the conductive-mixed group. Compared with a normal control group, there were only slight signs of benefit from separation of speech and noise in the region lateral to the listener, and virtually none in the frontal region. The new test, spatial separateness, had elements in common with both of the other tests, and links were observed from localization to separateness detection, and from separateness to benefit from separation of speech and noise. Localization was also related to speech hearing in nonspatially separated noise.