Effect of age on binaural speech intelligibility in normal hearing adults

Sentence perception performance, in quiet and in background noise, was measured in three groups of adult subjects categorized as young, middle-aged, and elderly. Pure tone audiometric thresholds, measures of inner ear function, obtained in all subjects were within the clinically normal hearing range. The primary purpose of this study was to determine the effect of age on speech perception: a secondary purpose was to determine if the speech recognition problem commonly reported in elderly subjects might be due to alterations at sites central to the peripheral nervous system inner ear. Standardized sentence lists were presented in free field conditions in order to invoke binaural hearing that occurs at the brainstem level, and to simulate everyday speech-in-noise listening conditions. The results indicated: (1) an age effect on speech perception performance in quiet and in noise backgrounds, (2) absolute pure tone thresholds conventionally obtained monaurally do not accurately predict suprathreshold speech perception performance in elderly subjects, and (3) by implication the listening problems of the elderly may be influenced by auditory processing changes upstream of the inner ear.