OOO Peace and quiet

Where do you think is silent? alone in a field? reading a book before bed? an awkward silence? well true silence comes in the form of a specially designed room, called an anechoic chamber. Here you experience background noise levels of -12.4dB [1]  comparing this to the noise levels described in my previous post, this is damn quiet  and as close to silence as it gets. So much so, you start to realise that your own body is a noisy bit of kit, making noises you probably didn’t realise it made.

Why is it quiet?

The room is this quiet due to its special design features. These include the room being built on springs with a low natural frequency, which prevents vibrations from being transmitted from the outside world. Once inside, it has a very specific design feature, this is that all the walls, ceiling and floor are covered with large foam wedges. These wedges are designed so no sound is reflected back to the listener. This is achieved by the sound entering both the foam material and areas in between the wedges, dissipating sound through friction.

The point of these rooms is for measurements, measurements such as loudspeaker response, microphone response or ear protection [1]

Here is a test subject in Salford universities anechoic chamber;

References:

BBC Manchester 27/08/09, The quietest room in the world [online], BBC News, P.1,  Available from: http://news.bbc.co.uk/local/manchester/hi/people_and_places/newsid_8224000/8224555.stm [Accessed: 9.3.2014]

 

Why wear ear plugs?????

As a musician, gig goer and acoustician noise levels appear frequently in my life, but what is so important about noise levels?

 

For example, ever go on a night out and wake up in the morning with ringing in your ears? If yes, then this is a short-term case of tinnitus, and is caused from the loud music and your friends shouting down your ears. How? In the inner ear, the hair cells are triggered by a sound wave entering the ear, (these hair cells convert the vibrations into an electrical pulse, that is sent to the brain) when there are exceptionally loud noises, these hair cells become damaged, and mistakenly send auditory information to the brain. In the case of a night out, I am sure you are aware the ringing is temporary and subsides after a few hours. This is because the damaged hair cells can repair themselves (given time).

 

If the noise was continuous over a large period of time, there is no respite, and the damage becomes permanent, the ringing doesn’t go away…

 

How loud?

 

I will give some examples of noise levels that we are exposed to;

 

Ringing telephone = 30dB

Normal conversation = 60dB

Lawn mower = 90dB

Chain saw = 110dB

Ambulance siren = 120dB

Rock concert = 140dB

12-gauge shotgun = 165dB

Night Club = 95-98dB

[1]

 

Is that loud then? Well consider that being exposed to sounds above 85dB for a repeated or long period of time can cause hearing loss.

 

So next time you go to a club or gig think about the potential damage you are causing your poor ears, simply wear ear plugs… and the problem goes away.

 

On a side note not only does loud music damaging to your ears, it may also lead to great dance moves…

 

References:

[1] – Cristen Conger N/A, WHY DO LOUD NOISES CAUSE YOUR EARS TO RING? [online], P.1,  Available from: http://health.howstuffworks.com/human-body/systems/ear/loud-noise-ear.htm [Accessed: 22.2.2014]