Supin Alexander Ya, Nachtigall Paul E, Breese Marlee
Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninsky Prospect, 119071 Moscow, Russia.
J Acoust Soc Am. 2010 Jun;127(6):3830-6. doi: 10.1121/1.3425733.
Evidence of varying hearing sensitivity according to the target distance was obtained in a false killer whale Pseudorca crassidens during echolocation. Auditory evoked potentials (AEPs) triggered by echolocation clicks were recorded. The target distance varied from 1 to 6 m. The records contained AEPs to the self-heard emitted click and AEPs to the echoes. Mean level of echolocation clicks depended on distance (the longer the distance, the higher the click level), however, the effect of click level on AEP amplitude was eliminated by extracting AEPs to clicks of certain particular levels. The amplitude of the echo-provoked AEP was almost independent of distance, however, the amplitude of the AEP to the emitted click, did depend on distance within a range from 1 to 4 m: the longer the distance, the higher the amplitude. The latter result is interpreted as confirmational evidence that the animal is capable of varying hearing sensitivity according to target distance. The variation of hearing sensitivity may help to compensate for the echo attenuation with distance; as a secondary effect, this variation manifested itself in a variation of the amplitude of the AEP to emitted clicks.
在伪虎鲸（Pseudorca crassidens）进行回声定位时，获得了其听力敏感度随目标距离变化的证据。记录了由回声定位咔哒声触发的听觉诱发电位（AEP）。目标距离在1至6米之间变化。记录中包含对自身发出咔哒声的AEP以及对回声的AEP。回声定位咔哒声的平均强度取决于距离（距离越长，咔哒声强度越高），然而，通过提取特定强度咔哒声的AEP，消除了咔哒声强度对AEP幅度的影响。回声诱发的AEP幅度几乎与距离无关，但是，对发出咔哒声的AEP幅度在1至4米范围内确实取决于距离：距离越长，幅度越高。后一结果被解释为动物能够根据目标距离改变听力敏感度的确证证据。听力敏感度的变化可能有助于补偿回声随距离的衰减；作为次要效应，这种变化表现为对发出咔哒声的AEP幅度的变化。
