Hoeffding V, Harrison J M
J Exp Anal Behav. 1979 Sep;32(2):157-66. doi: 10.1901/jeab.1979.32-157.
Rats were trained to respond on a lever adjacent to a sounding speaker (the sound source) when a single click was emitted. A second click (the artificial echo) was presented through a second speaker on the opposite side. In Condition I, the echo (equal in intensity to the source) was delayed from .015 to 32 milliseconds; greater than 75% correct responses were given for delay times between about .040 milliseconds (lower threshold) and 8 milliseconds (upper threshold). In Condition II, the echo (simultaneous with the source) was reduced in intensity relative to the source over a range from 2.5 decibels to 40 decibels; greater than 75% correct responses occurred for intensity reductions greater than 5 decibels. In Condition III, both the intensity and the delay time of the echo were manipulated in a manner analogous to that which would occur under natural conditions; greater than 95% correct responses were given for delay times from 1 to 32 milliseconds. These data indicate that both time and intensity differences are necessary for localization of primary sources, with delay time contributing more at short echo path distances, and intensity differences at long distances.
训练大鼠，使其在发出单次咔嗒声时，对靠近发声扬声器（声源）的杠杆做出反应。通过另一侧的第二个扬声器发出第二次咔嗒声（人工回声）。在条件I中，回声（强度与声源相等）延迟0.015至32毫秒；对于大约0.040毫秒（下限阈值）至8毫秒（上限阈值）的延迟时间，正确反应率超过75%。在条件II中，回声（与声源同时发出）相对于声源的强度在2.5分贝至40分贝的范围内降低；对于强度降低超过5分贝的情况，正确反应率超过75%。在条件III中，回声的强度和延迟时间都以类似于自然条件下会发生的方式进行操纵；对于1至32毫秒的延迟时间，正确反应率超过95%。这些数据表明，时间和强度差异对于主要声源的定位都是必要的，在短回声路径距离时延迟时间起的作用更大，而在长距离时强度差异起的作用更大。
