Mercedes-Benz' Pre-Safe Sound Preserves Drivers' Ears In A Crash

Have you heard, Mercedes-Benz is adding an unlikely safety feature to its upcoming 2016 E-Class automobiles: Pre-Safe Sound, an automated system designed to protect the inner ear from the shattering sound of an impact.

Pre-Safe Sound joins seatbelts, crumple zones, and airbags as the latest driver/passenger safety feature but unlike the others, the focus is one one specific area: our sense of hearing. The system works with a natural noise-protection attribute called the Acoustic Reflex; also known as the Stapedius Reflex, Middle-ear-muscles (MEM) Reflex, Attenuation Reflex or Auditory Reflex.

The reflex works by way of an involuntary muscular contraction of the stapedius and tensor tympani muscles located in the inner ear. By stiffening the “ossicular chain” - the connected series of tiny bones in the inner ear – the acoustic reflex acts to dampen the vibrational energy of loud sounds before the cochlea can convert them into electrical impulses sent on to the brain's aural processing center.

All well and good, but the Acoustic Reflex evolved long before the advent of automobiles and car crashes, the latter of which can occur in the blink of an eye – sorry for mixing metaphors. With Pre-Safe Sound, Mercedes-Benz is seeking to give Mother Nature a helping hand, er, so to speak.

Here's how it works: a specially designed ultrasonic sensor determines a crash is imminent, the car's audio system sends out a blast of white noise in the 85 decibel range.

It's loud enough to trigger the Acoustic Reflex, giving the inner ear sufficient time to protect itself from not only the sound of a crash but the noise of an exploding airbag (roughly 150-170 decibels)... yes, we're at the point where installed devices can provide protection from other installed devices designed to provide us protection. Xzibit would be proud. (via WIRED, Autonet, and