Bartsch E, Schmidt S
Zoologisches Institut, Universität München, FRG.
Hear Res. 1993 May;67(1-2):128-38. doi: 10.1016/0378-5955(93)90240-2.
Echolocating bats hunting flying insects discriminate complex temporal patterns of acoustic stimuli. For bats using frequency modulated sonar calls (FM bats), there are no behavioral data on the perception of sinusoidally frequency modulated (SFM) stimuli. Discrimination performance for SFM stimuli of varying modulation depth was measured in 4 Tadarida brasiliensis in a two-alternative, forced choice procedure. A center frequency of 40 kHz was modulated with rates between 10 and 2000 Hz. It was found that discrimination performance improved from a mean threshold modulation depth of 3.05 kHz at a modulation rate of 2000 Hz to 1.58 kHz at a modulation rate of 10 Hz. Psychoacoustical modulation depth thresholds of T. brasiliensis are thus distinctly larger than those observed in bat species emitting constant frequency (CF) components followed by an FM-sweep, in active echolocation experiments. The modulation thresholds of T. brasiliensis are discussed in connection with the ability of bats to discriminate insect wingbeats. A comparison between non-echolocating mammals and the FM bat T. brasiliensis shows that the ability to echolocate is not reflected in the modulation thresholds.
利用回声定位捕食飞行昆虫的蝙蝠能够辨别复杂的声学刺激时间模式。对于使用调频声纳叫声的蝙蝠（调频蝙蝠），目前尚无关于其对正弦调频（SFM）刺激感知的行为数据。在一个二选一的强制选择程序中，对4只巴西无尾蝠进行了不同调制深度的SFM刺激辨别性能测试。以40千赫的中心频率进行调制，调制速率在10至2000赫兹之间。结果发现，辨别性能从调制速率为2000赫兹时的平均阈值调制深度3.05千赫提高到调制速率为10赫兹时的1.58千赫。因此，在主动回声定位实验中，巴西无尾蝠的心理声学调制深度阈值明显大于那些发出恒定频率（CF）成分后接调频扫描的蝙蝠物种所观察到的阈值。结合蝙蝠辨别昆虫翅膀拍打的能力，对巴西无尾蝠的调制阈值进行了讨论。对非回声定位哺乳动物和调频蝙蝠巴西无尾蝠的比较表明，回声定位能力并未体现在调制阈值上。
