Human echolocators adjust loudness and number of clicks for detection of reflectors at various azimuth angles
Human echolocators adjust loudness and number of clicks for detection of reflectors at various azimuth angles
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DOI：
10.1098/rspb.2017.2735
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发表时间：
2018-02-28
影响因子：
4.7
通讯作者：
Hornikx, M.
中科院分区：
文献类型：
--
作者：
Thaler, L.;De Vos, R.;Hornikx, M.
研究表明，蝙蝠会根据情况需求调整排放量。在这里，我们报告了人类回声定位的类似发现。我们请八位盲人回声定位专家来检测位于不同方位角的反射器。将相同的直径为 17.5 厘米的圆形反射器放置在距离直线前方 08、458 或 908 处 100 厘米处时，检测到的准确度为 100%，但当放置在 1358（即稍微落后）时，性能下降到约 80%，而当放置在 1808（即正好落后）时，性能下降到机会水平 (50%)。这可以基于由于人嘴咔嗒声的波束图案而导致的较差的目标声化来解释。重要的是，对录音的分析表明，回声定位器在更远的角度增加了反射器的响度和喀哒声数量。当回声和发射之间的电平差异低至 227 dB 时，回声定位器能够可靠地检测反射器，这远低于根据以前的工作预期的值。增加强度和点击次数可以提高信噪比，从而补偿较弱的目标反射。据我们所知，我们的结果首次表明人类回声定位专家调整其发射以改善感官采样。我们的研究结果表明，人类回声定位器会从多个样本中积累信息。
In bats it has been shown that they adjust their emissions to situational demands. Here we report similar findings for human echolocation. We asked eight blind expert echolocators to detect reflectors positioned at various azimuth angles. The same 17.5 cm diameter circular reflector placed at 100 cm distance at 08, 458 or 908 with respect to straight ahead was detected with 100% accuracy, but performance dropped to approximately 80% when it was placed at 1358 (i.e. somewhat behind) and to chance levels (50%) when placed at 1808 (i.e. right behind). This can be explained based on poorer target ensonification owing to the beam pattern of human mouth clicks. Importantly, analyses of sound recordings show that echolocators increased loudness and numbers of clicks for reflectors at farther angles. Echolocators were able to reliably detect reflectors when level differences between echo and emission were as lowas 227 dB, which is much lower than expected based on previous work. Increasing intensity and numbers of clicks improves signal-to-noise ratio and in this way compensates for weaker target reflections. Our results are, to our knowledge, the first to show that human echolocation experts adjust their emissions to improve sensory sampling. An implication from our findings is that human echolocators accumulate information from multiple samples.