How Does Noise Work
By Susen Trail | 04/27/2020
How does noise work? You don’t have to take a physics class to know the phrase ‘sound waves’. This is a correct term to use when talking about noise.
You know when that car drives up beside you with the radio blaring and you can feel your car vibrate? It’s because noise creates pressure and pressure travels outward in a wave. That sound pressure is funneled into your ears and down into that snail looking cochlea where there are tiny little cilia that are called ‘hair cells’ because that’s what they look like.
The cochlea is full of liquid and the fibers. When the pressure waves go down the ear canal the pressure is transferred to the cochlea which cause the hair cells to move, like seaweed under a wave.
So, here’s the interesting thing, not all the hair cells move! The frequency of the sound determines how far up the spiral of the cochlea the sound wave will go and which hair cells are moved. That information is transmitted via the auditory nerve as frequency and volume.
Have you ever noticed that when you turn your car on in the morning the radio sounds really loud? This is because, by the time you headed for home you had tired your cilia out. Seriously, it’s called Auditory Fatigue, and overnight they rested up, hopefully, in the quiet of your house or while you were sleeping.
This is also called a Temporary Threshold Shift, meaning, the threshold at which you can hear a sound has to be louder just to get the cilia to react. Now, when the radio sounds just fine, the loss may be permanent, a Standard Threshold Shift.
For more information on employee exposure to noise go to Noise, Adverse Effects, and OSHA Compliance