Relationship of Auditory Distortion Test Results to Speech Discrimination through Flat vs. Selective Amplifying Systems.

Thirty adult subjects with high frequency hearing loss were given speech discrimination tests under conditions of flat and selective amplification. It was hypothesized that performance for the two amplifying conditions is related to amount of distortion in the auditory system as defined by selected clinical tests. An assumption was made that excessively distorted auditory systems are more easily overdriven by high frequency emphasis amplification than auditory systems with less distortion. Therefore, subjects with least distortion were expected to discriminate speech better through a high-pass filtered amplifying system which, within limits, restored frequency-intensity balance. Results indicated slightly better speech discrimination performance for the selective amplifying condition. There was some evidence that the extent of the difference favoring selective amplification may be influenced by the amount of distortion in the auditory system.