Processing of noise by single units of the inferior colliculus of the bar Rhinolophus ferrumequinum.

For inferior colliculus units the response patterns and the thresholds for pure tones and noise of variable bandwidth were determined. In a threshold-bandwidth plot the noise thresholds usually fell along two regression lines whose point of intersection established the size of the neuronal critical bandwidth (nCB). The relevance of the small nCBs (0.2-0.4 kHz) obtained for the frequency range of the constant frequency part of the orientation call is discussed. No fixed relation was found either between the nCBs and the neuronal critical ratios or between the size of nCB and the width of the tuning curve 3 dB above threshold of the best frequency.