All phases of the experiment were conducted with animals in a wire mesh alley (30.5 × 5.8 × 6.0 cm) tilted at ∼20° so that the subject’s head was above its body (for details see Headley andWeinberger 2011). The alley sat atop a weighted table inside an acoustic isolation chamber (Industrial Acoustics). Elastic bands attached to the cage could be threaded through metal loops in the skullcap to restrict head movements during training and delivery of acoustic stimuli.