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How Pink Noise Can Protect Your Hearing

And why Mercedes is using it in new "pre-crash" technology


Although most of us probably cannot run out and buy the new 2017 E-Class Mercedes-Benz (suggested retail price: $52,150 and up), there’s some interesting new technology in it that you may want to know about. According to IEEE Spectrum, when this Mercedes detects the car is about to crash, it deploys a burst of “pink noise” causing an inner-ear muscle called the stapedius to contract and brace the eardrum for the earsplitting noise of the crash itself.

Pre-crash safety features in cars are not new (IEEE Spectrum cites seatbelts that instantly tighten or sunroofs that instantly close when a crash is predicted), but the notion of pink noise as a means of protecting hearing is novel. Mercedes describes this feature as “Pre-Safe Sound” (you can hear it yourself in Mercedes’ video).

IEEE Spectrum reports that the pink noise being used is approximately 80 decibels — “about equal to that of a dishwasher and completely safe.” Car crashes, IEEE explains, are potentially deafening and usually register around 145 decibels. “Worse still — and this part is not emphasized by Mercedes-Benz or any other carmaker — is the noise created by the near-instantaneous deployment of the airbag: around 165 dB,” writes Philip E. Ross. “It’s estimated that 17 percent of the people who are exposed to airbag deployment suffer some degree of permanent hearing loss.”

It’s estimated that 17 percent of the people who are exposed to airbag deployment suffer some degree of permanent hearing loss

— Philip E. Ross, IEEE Spectrum

What Is Pink Noise?

Most of us have heard of white noise; white noise machines and apps flood rooms with something that sounds like old-fashioned broken TV static. The machines are often used as sleep aids and to mask tinnitus. Technically speaking, white noise is really a combination of all of the different frequencies of sound.

Pink noise refers to a broad spectrum of frequencies in which the power is inversely proportional to the frequency. If you skipped college physics and listened to a lot of records instead, you might better understand pink noise as using different octaves of the same tone in which each of the octaves has the same frequency power as the other. Because of this, a lot of people hear pink noise as being “even” or “flat,” but the difference between white and pink noise is difficult for most people to detect. Mercedes describes it in its marketing materials as “a bit like diffuse traffic noise, the breaking of waves or a waterfall.”

(Just think about how you might panic upon hearing ocean waves during a car crash if you weren’t aware of this feature, though.)

Can Pink Noise Protect Against Hearing Loss?

Mercedes’ use of pink noise raises the question of whether the same technique might be used to trigger muscles in the ear to brace the inner ear from other loud noises and prevent hearing loss. The threshold to trigger the stapedius reflex is around 100 decibels, which is quite loud. Pink noise, however, allows that noise to be spread across the spectrum and doesn’t feel as jarring to our ears. However, it only triggers a quick muscle reflex lasting just about a second.

In other words, loud bursts of pink noise probably could not prevent hearing loss over time or in many other cases. In fact, it could be detrimental to hearing if used loudly over time. However, some hearing aids use pink noise (as well as white noise, high-tone noise and other noise) to help people who suffer from tinnitus to reduce or diffuse the ringing in their ears.

Protect Your Hearing, Protect Your Brain

New pre-safety measures like the pink noise deployment in the Mercedes E-Class could usher in a new level of hearing protection safety in automobiles. And perhaps other uses of the technology can be developed and used beyond just high-end vehicle safety (for example, maybe workplaces prone to loud bursts of sound might investigate other uses of bursts of pink noise or the military could use the technology where loud explosives and guns are used).

Considering the connection between hearing loss and dementia, as well as the social isolation experienced by many who have lost their hearing, any additional measures that protect hearing seem worthy of research and investment.

 

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