Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
J Assoc Res Otolaryngol. 2013 Apr;14(2):261-73. doi: 10.1007/s10162-012-0367-7. Epub 2013 Jan 15.
Several studies have attributed deterioration of sound localization in the horizontal (azimuth) and vertical (elevation) planes to an age-related decline in binaural processing and high-frequency hearing loss (HFHL). The latter might underlie decreased elevation performance of older adults. However, as the pinnae keep growing throughout life, we hypothesized that larger ears might enable older adults to localize sounds in elevation on the basis of lower frequencies, thus (partially) compensating their HFHL. In addition, it is not clear whether sound localization has already matured at a very young age, when the body is still growing, and the binaural and monaural sound-localization cues change accordingly. The present study investigated sound-localization performance of children (7-11 years), young adults (20-34 years), and older adults (63-80 years) under open-loop conditions in the two-dimensional frontal hemifield. We studied the effect of age-related hearing loss and ear size on localization responses to brief broadband sound bursts with different bandwidths. We found similar localization abilities in azimuth for all listeners, including the older adults with HFHL. Sound localization in elevation for the children and young adult listeners with smaller ears improved when stimuli contained frequencies above 7 kHz. Subjects with larger ears could also judge the elevation of sound sources restricted to lower frequency content. Despite increasing ear size, sound localization in elevation deteriorated in older adults with HFHL. We conclude that the binaural localization cues are successfully used well into later stages of life, but that pinna growth cannot compensate the more profound HFHL with age.
几项研究将水平（方位）和垂直（仰角）平面声音定位的恶化归因于与年龄相关的双耳处理能力下降和高频听力损失（HFHL）。后者可能是老年人仰角表现下降的原因。然而，由于耳廓在整个生命过程中不断生长，我们假设较大的耳朵可以使老年人根据较低的频率在仰角定位声音，从而（部分）补偿他们的高频听力损失。此外，当身体仍在发育并且双耳和单耳声音定位线索相应变化时，声音定位是否已经在非常年轻的时候成熟尚不清楚。本研究在二维前半球场的开环条件下调查了儿童（7-11 岁）、年轻人（20-34 岁）和老年人（63-80 岁）的声音定位性能。我们研究了与年龄相关的听力损失和耳朵大小对不同带宽的短暂宽带声音脉冲的定位响应的影响。我们发现所有听众（包括高频听力损失的老年人）在方位上的定位能力相似。对于耳朵较小的儿童和年轻听众，当刺激包含 7 kHz 以上的频率时，声音在仰角的定位会得到改善。耳朵较大的受试者也可以判断声源的仰角仅限于较低的频率内容。尽管耳朵尺寸不断增大，但高频听力损失的老年人在仰角的声音定位仍会恶化。我们的结论是，双耳定位线索在生命的后期阶段得到了很好的利用，但耳廓的生长不能随着年龄的增长补偿更严重的高频听力损失。
