No abstract

Biophysics and Physicobiologyhttps://www.jstage.jst.go.jp/browse/biophysico/

No abstract

To investigate the performance of horizontal sound localization of elderly people, authors conducted a test using 19 elderly participants (10 males, 9 females; ages 65-85; mean 71.5 years old.) The stimuli were presented through headphones to their right and left ears with 4 interaural time differences (ITDs) (0.2, 0.4, 0.6, and 0.8 ms) and 4 interaural level differences (ILDs) (3, 6, 9, and 12 dB(A)) besides the same condition to both ears. Concerning the frequency, pure tones of 1.0 and 2.0 kHz, and composite sound of 0.5 + 2.0 kHz were presented, which lasted one second for each trial. The participants answered “Right” or “Left” after each trial according to their own judgment. The results of ITD condition showed that in case of the pure tones a right-sided inferiority was recognized, which was poorer than the results of the younger participants. Meanwhile, no right/left difference was recognized with the composite sound. Concerning the ILD condition, no right/left asymmetricity was shown. Furthermore, no significant differences were recognized regarding the relationships between their sound localization performance and potential influential factors. The factors were Trail Making Test (TMT) results, their preferred ear, and their hearing loss difference between right/left ears.

To investigate the performance of horizontal sound localization of younger people, authors conducted a test using 12 young participants (11 males, 1 females; ages 21–24.) The stimuli were presented through headphones to their right and left ears with 4 interaural time differences (ITDs) (0.2, 0.4, 0.6, and 0.8 ms) and 4 interaural level differences (ILDs) (3, 6, 9, and 12 dB(A)) besides the same condition to both ears. Concerning the frequency, pure tones of 0.5, 1.0, and 2.0 kHz, and composite sound of 0.5 + 2.0 kHz were presented, which lasted one second for each trial. The participants answered “Right” or “Left” after each trial according to their own judgment. The results of ITD condition showed that a right-sided inferiority was recognized in case of 1.0 and 2.0 kHz. Concerning the ILD condition, no right/left asymmetricity was shown. This asymmetricity may be caused by the improper setting of the experiment apparatus. Therefore, we switched right/left of the headphones to carry out an additional test in the same way. The same tendency as the original test was obtained, which means that the asymmetricity is likely due to the native characteristics of the participants.