A compressive nonlinearity in the mechanics of the cochlea is responsible for (1) the dynamic detection range of about 120 dB; (2) the level-dependent modification of the ability to detect one tonal component in the presence of another (masking); (3) the stabilization of cochlear self-oscillations, which are associated with sounds broadcast from the ear (spontaneous otoacoustic emissions); and (4) the psychoacoustic detection and detection in the ear canal of frequency components (intermodulation distortion products) not present in the original acoustic signal. The spontaneous otoacoustic emission spectra are characterized by quasi-regular frequency spacings, with some ears having over 30 narrow-band spectral peaks. The intermodulation distortion level is higher than that claimed for mediocre stereo systems and varies with frequency. Several interesting analogies between the modeling of otoacoustic emissions and the sound spectra of musical wind instruments are discussed. [Work supported by NIDCD.]