Institut de Recherche Biomédicale des Armées, Département Action et Cognition en Situation Opérationnelle, BP 73, 91223 Brétigny sur Orge Cedex, France.
Hear Res. 2013 Oct;304:20-7. doi: 10.1016/j.heares.2013.06.001. Epub 2013 Jun 12.
Individual differences exist in sound localization performance even for normal-hearing listeners. Some of these differences might be related to acoustical differences in localization cues carried by the head related transfer functions (HRTF). Recent data suggest that individual differences in sound localization performance could also have a perceptual origin. The localization of an auditory target in the up/down and front/back dimensions requires the analysis of the spectral shape of the stimulus. In the present study, we investigated the role of an acoustic factor, the prominence of the spectral shape ("spectral strength") and the role of a perceptual factor, the listener's sensitivity to spectral shape, in individual differences observed in sound localization performance. Spectral strength was computed as the spectral distance between the magnitude spectrum of the HRTFs and a flat spectrum. Sensitivity to spectral shape was evaluated using spectral-modulation thresholds measured with a broadband (0.2-12.8 kHz) or high-frequency (4-16 kHz) carrier and for different spectral modulation frequencies (below 1 cycle/octave, between 1 and 2 cycles/octave, above 2 cycles/octave). Data obtained from 19 young normal-hearing listeners showed that low thresholds for spectral modulation frequency below 1 cycle/octave with a high-frequency carrier were associated with better sound localization performance. No correlation was found between sound localization performance and the spectral strength of the HRTFs. These results suggest that differences in perceptual ability, rather than acoustical differences, contribute to individual differences in sound localization performance in noise.
即使对于正常听力的听众，声音定位性能也存在个体差异。其中一些差异可能与头部相关传递函数 (HRTF) 所携带的定位线索的声学差异有关。最近的数据表明，声音定位性能的个体差异也可能具有知觉起源。听觉目标在上下和前后维度上的定位需要对刺激的频谱形状进行分析。在本研究中，我们调查了声学因素（频谱形状的显著性“频谱强度”）和知觉因素（听众对频谱形状的敏感性）在声音定位性能个体差异中的作用。频谱强度是通过 HRTF 的幅度谱与平坦谱之间的频谱距离计算得出的。使用具有宽带（0.2-12.8 kHz）或高频（4-16 kHz）载波的频谱调制阈值和不同的频谱调制频率（低于 1 个倍频程、1 到 2 个倍频程之间、高于 2 个倍频程）来评估对频谱形状的敏感性。从 19 名年轻的正常听力听众中获得的数据表明，高频载波下低于 1 个倍频程的频谱调制频率的低阈值与更好的声音定位性能相关。HRTF 的频谱强度与声音定位性能之间没有相关性。这些结果表明，在噪声中，感知能力的差异而不是声学差异，导致了声音定位性能的个体差异。
