Maj Stephen Steele
The ability to localize and segregate sound sources depends on innate functioning of the binaural hearing system. Peripheral and central functions of the auditory nervous system contribute to overall spatial hearing function. Three techniques are described that measure one’s ability to localize and attend to multiple sounds. One is a head pointing task to measure localization acuity in azimuth. A second is an exocentric sphere pointing task to measure localization performance in azimuth and elevation. A third task is used to measure one’s ability to identify words in the presence of a spatially separated speech masking sound. Behavioral data has been collected on normal hearing and hearing impaired individuals using these three techniques. With the head pointing technique, good localizers (81%) were measured to have a median acuity of 6 degrees, moderate localizers (17%) around 12 degrees, and poor localizers (2%) above 15 degrees of angular error. The sphere pointing task is more sensitive than the head pointing task to the degrading effects of hearing loss. Spatial separation greatly improved speech intelligibility for normal and hearing impaired listeners. The multiple talker task involved spatial hearing and cognitive abilities and is perhaps the most relevant to real world tasks.