This Is Your Brain on Music: The Science of a Human Obsession

by Daniel J. Levitin

Our ears compress sounds that are very loud in order to protect the delicate components of the middle and inner ear. Normally, as sounds get louder in the world, our perception of the loudness increases proportionately to them. But when sounds are really loud, a proportional increase in the signal transmitted by the eardrum would cause irreversible damage. The compression of the sound levels—of the dynamic range—means that large increases in sound level in the world create much smaller changes of level in our ears. The inner hair cells have a dynamic range of 50 decibels (dB) and yet we can hear over a 120 dB dynamic range. For every 4 dB increase in sound level, a 1 dB increase is transmitted to the inner hair cells. Most of us can detect when this compression is taking place; compressed sounds have a different quality.