Input-output functions of the physiological measures at 4 kHz before (solid circles) and 2 wk after (solid triangles) carboplatin injection. (A) cochlear microphonics; (B) distortion product OAEs; (C) summating potential; (D) compound action potential. All points are averages for all eight chinchillas, with the following exceptions: Pre-carboplatin: CM: 0 dB SPL, n = 2; 5 dB SPL, n = 4; CAP: 5 dB SPL, n = 2; 10 dB SPL, n = 7. Post-carboplatin: CM: 0 dB SPL, n = 4; 5 dB SPL, n = 5; CAP: 10 dB SPL, n = 3; 15 dB SPL, n = 3; 20 dB SPL, n = 7.