Stereocilin-deficient mice reveal the origin of cochlear waveform distortions

The key to sound distortion The mammalian ear, or rather its auditory organ the cochlea, is a remarkably sensitive and finely tuned acousto-electrical transducer. It also markedly distorts sounds, and counter-intuitively it is this latter characteristic that gives rise to the masking effect that improves speech intelligibility in the human ear. Until now, the origin of these distortions was unknown. The mammalian cochlea possesses two types of hair cells — inner and outer hair cells. In experiments in mice, Verpy et al. show that it is the outer hair cells that introduce the distortion; the nonlinearity arises in the 'top connectors' between outer hair cell sterocilia known as, and more specifically, in a protein called stereocilin.