Anexperiment was conducted to determine the effect of aging onsound localization. Seven groups of 16 subjects, aged 10–81 years,were tested. Sound localization was assessed using six different arraysof four or eight loudspeakers that surrounded the subject inthe horizontal plane, at a distance of 1 m. Fortwo 4-speaker arrays, one loudspeaker was positioned in each spatialquadrant, on either side of the midline or the interauralaxis, respectively. For four 8-speaker arrays, two loudspeakers were positionedin each quadrant, one close to the midline and thesecond separated from the first by 15°, 30°, 45°, or60°. Three different 300-ms stimuli were localized: two one-third-octave noisebands, centered at 0.5 and 4 kHz, and broadband noise.The stimulus level (75 dB SPL) was well above hearingthreshold for all subjects tested. Over the age range studied,percent-correct sound-source identification judgments decreased by 12%–15%. Performance decrements wereapparent as early as the third decade of life. Broadbandnoise was easiest to localize (both binaural and spectral cueswere available), and the 0.5-kHz noise band, the most difficultto localize (primarily interaural temporal difference cue available). Accuracy wasrelatively higher in front of than behind the head, anderrors were largely front/back mirror image reversals. A left-sided superioritywas evident until the fifth decade of life. The resultssupport the conclusions that the processing of spectral information becomesprogressively less efficient with aging, and is generally worse forsources on the right side of space. ©2000 Acoustical Societyof America.
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