SV1000 CCC cans <98db?

[Mr Speirs]

Just to clarify Weighting in Decibel meter has nothing to do with length of noise (i.e. the 8hrs Supervox is talking about) it is merely a sort of filter which disregards certain frequencies.

A weighting starts to attenuate frequencies below 1kHz on a sliding scale. So when you get down to 100hz the meter is attenuating that frequency at -20db and therefore pretty much disregards low end frequency on SPL measurements, this is particularly useful for us V-Twin owners

The reason A weighting is used is the human ear naturally compresses low frequencies so there would be no point to measuring SPL's of low end frequency if it isn't being perceived by humans at the same level.

The difference between C weighting and A weighting is that if you had a 100Hz tone and measured that, A-weighting would show it roughly 20db quieter than C-weighting.

A weighting - Starts Attenuating below 1kHz
B Weighting - Starts Attenuating at around 500Hz
C Weighting - Is pretty much flat all the way down to 40Hz
D- Weighting - Is bonkers, Attenuates below around 80Hz and then boosts anything above 1.5kHz by 10db

[Supervox]

I didn't know that Mr S !!

At work there are 2 figures used when used for noise measurement - 85DbA which is the figure used when looking at constantly noisy tasks & 135DbC when looking at single (or a series of single) bangs.

[Mr Speirs]

Originally Posted by Supervox

I didn't know that Mr S !!

At work there are 2 figures used when used for noise measurement - 85DbA which is the figure used when looking at constantly noisy tasks & 135DbC when looking at single (or a series of single) bangs.

Whilst I don't doubt that this is the regulations in your workplace I do doubt the validity and reasoning behind the weighting.

Eu regs are that if you are subjected to 85dbA for more than 20mins then earprotection must be provided by the employer and worn by the employee. Which makes sense over the period of time. One off noises should have a limit also but again there should be no reason to measure these in anything other than A-weighted.

Would actually be interested in the reason why it is measured C-weighted if you have the ability to find out?

[Supervox]

I shall see what I can do - however, they may be only so much that I can put on a public forum.

[chris8886]

Originally Posted by wyrdness

Thruxton isn't exactly far from Fleet. It's under 40 miles.

as far as i'm aware thruxton don't do public track days

[Mark_h]

Well, Just got up to a damp, grey Derbyshire and thought I'd see if the sound tester was at the circuit today. Luckily he was. I explained the situation and after a cup of coffee he tested me for noise. The DB-C tester from Maplin gave c120db. His official DB-A tester gave me 88db one side and 89db the other so we're all good to go.

Will need to be "officially" tested tomorrow but should not be a problem.