[Application of the lateralization sound test in elderly individuals]

The ability to determine the direction of a sound source is based on the fact that sounds reach both cars at different times, phase, intensity and/or frequency. The perception of a sound source favors speech intelligibility in noisy environments.

To identify the minimum time of interaural delay--produces lateralization to the car which the stimulus reached first--through ascendant and descendent techniques, using the Sound Lateralization Test in elderly individuals with normal hearing thresholds in the frequencies which are most important for speech comprehension.

The Lateralization Test was used in 30 individuals with ages above 60 years, who presented hearing thresholds up to 25 dBHL in 500, 1000 and 2000 Hz and with no air-bone gap.

Mean times of interaural delay in sound lateralization were: a) ascending technique: 125.56 sec. (female) and 83.61 sec. (male); b) descending technique: 95.06 sec. (female) and 61.68 sec (male).

There is no difference between the mean time of interaural delay in sound lateralization obtained with the ascending or descending technique regarding the variable initial tested ear (right or left ear); the mean time of interaural delay in sound lateralization is smaller in males, when considering both ascendant and descendent techniques; the mean time of interaural delay in sound lateralization obtained with the descendent technique is smaller than that obtained with the ascendant technique; individuals who present hearing losses beginning at 3000 Hz have smaller mean times of interaural delay in sound lateralization than normal hearing individuals in both techniques.