Using pink noise technology to protect hearing

Pink noise corresponds to sound with a broad spectrum of frequencies in which the power is inversely proportional to the frequency. To most people, pink noise is perceived as even or flat sound. Mercedes is using pink noise at about 80 dB, a non-harmful level similar to that of a dishwasher, or a freight train passing by at 15 meters away.

The idea behind the pre-crash safety technology is that the vehicle will emit pink noise at this level just before an imminent car accident in order to prepare the ear for the potentially deafening noise of the crash. The burst of pink noise causes the stapedius inner-ear muscle to contract and brace the eardrum for the much louder noise expected from the crash and deployment of the airbag.

Importantly, the noise from the crash can register at 145 dB, a level above that recorded when a jet aircraft takes off from an aircraft carrier. Also, the noise created by the near-instantaneous deployment of the airbag is about 165 dB, and it is estimated that 17% of people exposed to airbag deployment suffer some degree of permanent hearing loss, the article reports.

Applying the muscle-reflex technology is complex because the protection from bursts of pink noise is short-lived, and higher or prolonged exposure may be damaging in and of itself. Possible areas of use, however, could include the occupational arena and the military environment.