Noral D. Stewart <noral at ix.netcom.com> wrote in article
<32851F28.420A at ix.netcom.com>...
> Eshet wrote:
> > Hello to all.
> > i'm interested in the transition from noise spectrum to the level of
> > annoyance. I have measured noise spectrum in dBSPL and i want to find
> > that noise cause damage to whom who listens to it.
> > i know that there are graphs and tables for it, but i am looking for a
> > defined algorithm and maybe a computer program for the calculation.
> > also, are there any formulas, instead of graphs for calculating dB(A)
> > dBSPL.
> > Thanx.
> > Itay (yaele at post.tau.ac.il)
>> This may be more appropriate for posting in alt.sci.physics.acoustics.
> I will forward it there.
>> Computing A-weighted sound level from octave band or third octave
> data is simply a matter of applying the proper weighting to each band,
> dividing each band result by 10, taking the antilog of each, summing all
> the band antilogs, then taking the log of the sum and multiplying by 10.
I have been working on just such a program which should hopefully be
available within a few days at our web software site.
> Annoyance and physical damage are two different effects of noise.
> A third is interference with activity such as speech or sleep. The most
> certain physical damage is that to hearing from exposure to very loud
> noise. Activity interference can occur at lower levels. Annoyance
> results partially from activity interference. However, it can also
> result from deterioration of the acoustical quality of the environment
> that can occur at very low levels. There is much research on these
> aspects of noise in the literature. Try the Journal of the Acoustical
> Society of America, Journal of Sound and Vibration, or Acustica.
The percentage of a population subject to a particular hearing loss will be
dependent on noise exposure and age. If you have a recent browser such
as Netscape 2/3 or MS Internet Explorer 3 check out:
Enviro at measure.demon.co.uk