Audibility Thresholds of a Sound Reflection in a Classical Human Echolocation Experiment

作者：Pelegrin Garcia David^*; Rychtarikova Monika^*; Glorieux Christ^*

来源：Acta Acustica United with Acustica, 2016, 102(3): 530-539.

DOI：10.3813/AAA.918970

Given the renewed interest in human echolocation research, the results of a classical psychophysical experiment by Rice et al. [J.Exp.Psychol. 70, pp. 246-251 (1965)] are revisited to derive the audibility thresholds of a single acoustic reflection in a human echolocation task, namely the detection of a reflecting disk in front of a blind person by using self-generated sounds. In the present work, the strength of the reflections caused by the disks in the original experiment is quantified by means of acoustic measurements of the airborne sound transmission from the mouth to the ears using a dummy head. A single-number metric, the Reflected-to-Direct Level Difference (RDLD), which uses the spectrum of a typical human echolocation signal and the inverted 40 phon equal-loudness level contour as weighting functions, is used for quantifying the reflection strength. The audibility thresholds for the sound reflections are re-interpreted in terms of RDLD, achieving typical values of 22 to 19 dB for reflection delays between 4 and 15 ms. These values are notably lower than single-reflection threshold values for externally played musical passages, found in the literature of subjective room acoustics, suggesting a superior performance of blind echolocators in actively identifying echoes with tailored signals.

• 出版日期2016-6