Voyage au centre de l'audition : spécialistes

> Watch out ! Danger !

Drawings and animation: S. Blatrix ; scientific contributors: M. Camilleri, J. Ducourneau

The cochlea is fragile: it needs to be protected ! Among the risk factors, the greatest is intense noise !
Exposure to high noise levels irreversibly destroys our sensory cells and produces deafness and tinnitus.

The number one enemy: noise !
The animation represents the havoc caused by too loud a sound (noise) on one of our sensory cells. Up to 80-85 decibels, the cells (and our auditory sensation) do not suffer. Above this level, there are hairs which are gradually destroyed and then disappear totally: the cells dies and there is no longer any auditory sense: this is deafness.

	Watch out ! At birth our cochlea contains less than 15,000 hair cells, a very limited capital (regarding to the millions of sensory cells in the retina). And these cells, since their are killed (by the noise) do not regenerate!

Sound exposure and DANGER for the ear !

This sound level scale (in dB) classifies the sounds in our environment into four categories :

	- Up to 80 dB (green): there is no risk for the ear, regardless of the duration of the sound exposure
	- From 80 to 90 dB (yellow): we are getting closer to the danger zone, but the risks are limited to very long exposures.
	- From 90 to 115 dB (red): the danger zone: the louder the sound the less time is needed for damage to occur.
	- Above 115 dB (brown), very brief sounds immediately cause irreversible damage.

Dangerous sounds and noises: relation between level/duration and the law

Sound levels damaging the cochlea are indicated here, regarding the European Legislation.
An emphasis is made on the time limit exposure for each dangerous level.

See: directive 2003/10/CE of the European Parliament, 06/02/2003

You can see that current law doesn’t necessarily protect our ears!

	- By limiting the sound level at nightclubs to 105 dB, we may be protecting the neighbours, but not the punters who shouldn’t expose themselves to 100 dB for more than half an hour! DJs are starting to understand this: take a good look at their ears… generally they’re protected!
	- Limiting the output of an MP3 player to 100 dB is a good thing, but it should be pointed out that listening to it for more than 2 hours a day at 90 dB is dangerous!
	- Regarding work legislation, if it is generally perfectly applied and followed in factories and airports, it won’t help the care-free handyman who happily uses nail guns, circular saws and grinders without protection!
	- Similarly, although ear defenders are required in shooting galleries, what hunter ever thinks about wearing earplugs?

> Watch out ! Danger !

The number one enemy: noise !

Sound exposure and DANGER for the ear !