Fig. 9. A typical big brown bat echolocation sound (left) with sharpness of frequency tuning for neurons in the bat's cochlear nucleus (CN) and inferior colliculus (IC) [replotted from Haplea et al. (Haplea et al., 1994)]. The horizontal broken line indicates where the sweep tails off in the first harmonic at approximately 23 kHz. With no other constraints, frequencies within this range are used for target detection. In this example, IC tuning is much sharper at frequencies around 23–25 kHz, with Q_10dB values ranging from 2 to 40, and some as high as 90.