The percentage of single units in each unit-type category as defined by responses to 20 dB SL, best frequency tonebursts [i.e. build-up, primary like (PL), onset, chopper, pauser-build-up (P-B), unusual and low frequency (LF)] for control (N = 57) and noise-damaged (N = 49) animals. Noise-damaged animals include 1 and 2 weeks post-damage combined. All ‘unit types’ observed in the normal animals are also observed in the noise-damaged animals. However, the proportion of chopper units was significantly increased, whereas the proportion of build-up units was significantly decreased in the noise-damaged animals (χ2 = 84, 6 d.f., P < 0.001).