Sound Limits

[teenypops]

I am seeking some advice and hope that someone may know the answer or where I can find the answer.

I was wondering if there were any recommended noise level limits for children and if so what are they.

I do kids discos, but currently do not limit the sound level, but I feel it should be my duty to do so. I am getting a sound meter so that I can measure the level, but just want to know any guidelines.

Thanks in advance

[Dynamic Entertainment]

American site...but gives you the jist of it....

http://www.childrenshearing.org/custom/hearing_health.html

Exceprt from the page linked to:



Decibels measure the loudness of sound. Both the amount of noise and the length of time of exposure determine the amount of damage. Damage can be caused to hair cells of the inner ear and the hearing nerve by one-time exposure to loud sounds like an explosion or by continuous or repeated exposure to noise. Sounds that are less than 80 decibels are unlikely to cause hearing loss. Noise levels greater than 80 decibels can be hazardous and can damage your hearing. Many experts agree that continual exposure to more than 85 decibels is hazardous to your hearing.

[teenypops]

Really helpful thanks

[teenypops]

Looking ay "Dynamics" site I used some of the search terms and found this article from the Mail.

http://www.dailymail.co.uk/health/article-58247/How-loud-loud.html

Amazing I have been hunting for the last few days and just like buses...

[Pink Elephant]

Good sources of info.

The Mail one says "Sound is measured in decibels (dB), and an increase or decrease of 10dB represents a doubling or halving of loudness. That means 80dB is twice as loud as 70dB" this is incorrect - the doubling of sound is 3dB step.

A 10dB step is approximately 10x louder :eek:

I tend to keep it low for the infant school ages, a little louder for juniors and normal level for senior school. As for 18ths ..... :daft:

Have fun :p

[djeddie]

A 10dB step is approximately 10x louder

In a previous post I was accused of "not showing my working out" so...

Doubling power is an increase of 3 dB while doubling amplitude is an increase of 6 dB.

In electrical engineering terms, where power is measured in watts:-

dB = 10 log p1/p2

and amplitude is measured in volts:-

dB = 20 log v1/v2

The log of 2 is about .3, so when the ratio is 2:1 (either halving or doubling), the formulae work out as 10 * 0.3 (for power) and 20 * 0.3 (for amplitude), leading to the aforementioned 3 dB and 6 dB.

However a doubling in power doesn't necessarily lead to a doubling in audible perception. For most people 10db is the perceived doubling or halving of loudness.

A speaker producing an SPL of 120dB with 500W input will be 117dB with 250W input, a 3dB decrease. The difference will be noticeable yes, but most people will not think it has "halved in volume".

The real story can only be explained if the correct term is used, such as dBm, dBu, dBa, dBspl, dBFS etc etc.

[Corabar Entertainment]

In a previous post I was accused of "not showing my working out" Absolutely no need to be rude and twist things. As you well know, that's not what I said at all. :( :(

[djeddie]

Absolutely no need to be rude and twist things. As you well know, that's not what I said at all. :( :(

My sincerest apologies. It wasn't meant to be rude.

[Corabar Entertainment]

Apology accepted :)

[addoaddo]

With the current regulations there is no limit to the noise exposure for guest only for Employees.
85dB is generally seen at the level that you can start to get problems. Generally you will find that the parents soon complain if they think their little darlings are being exposed. For children I would keep the level to around 80dB but in addition have breaks in the music, so every so often play a quitter track to give the ears a rest.
Sound is also always measured at a specific point. For example speakers are often quoted at a dB level 1 m from the speaker. An 83dB level at the speaker could easily be 80dB on the dance floor and 75dB at the back of the room.
I use a sound level meter (SPL meter) on my iPhone. Although not 100% calibrated gives you a good idea of the levels

[djeddie]

For example speakers are often quoted at a dB level 1 m from the speaker. An 83dB level at the speaker could easily be 80dB on the dance floor and 75dB at the back of the room.

Sound pressure is subject to inverse-square theory, meaning that as you double the distance you halve the sound. So to use your example, if the SPL at the speaker (not 1m away, that's something entirely different) is 83dB then at 2m away it will be 77dB and at 4m away it will be 71dB etc etc. At the back of the room it will be slightly different as the reverberation will add to the direct sound.
The 1m measurement is part of the specifications of the loudspeaker. It's supposed to be so you can compare, but many manufacturers will use a level that you wouldn't normally use the driver for. Such as the Eminence ME15-300 driver was advertised as being 103dB 1W/1m. It achieved the 103dB at 2Khz, which is a bit out of the usable range of the driver due to beaming, while in it's usable range (up to about 1KHz) it only achieved 97dB!