I agree that adding white noise to the room is
useless.
In recent years, noise cancellation technology has
made great progress, and I believe the airline
industry uses active noise-cancelling 'earmuffs' now
for the ground crews.
However, the foam panels would be cheaper.
--- Brian Ellis <[log in to unmask]> wrote:
> Steve
>
> Gobble-de-gook, codswallop or BS it is, IMHO. There
> is NO way by adding sound to a
> noisy environment can you reduce the sound level. If
> the before sound level is such
> that comfort/health is compromised and you add
> sufficient white noise to mask it, then
> the after sound level would be a good 10 dB higher,
> possibly sufficient to bust your
> eardrums.
>
> In any case, air flowing out through a non-resonant
> nozzle will produce what? White
> noise! (OK, for air knives, there will also be some
> cyclic noise, as well, generated by
> the ventilator blades, and you may have some minor
> resonances.)
>
> What your guy may be thinking of is
> noise-cancelling, but this is also irrelevant here.
> This consists of adding a cancelling variation of
> air pressure to those produced by the
> noise source. It does not work well with white noise
> as it is impossible to predict, by
> definition, when the next high or low pressure will
> take place. It is also very
> positionally sensitive in three dimensions,
> depending on the frequency, spacing between
> the primary and secondary sources, position of the
> pick-up microphone, etc.
>
> Forget all this and buy those insulation panels.
>
> Brian
>
> "Stephen R. Gregory" wrote:
>
> > Hi ya'll!!
> >
> > This post may be a little strange, but I'll ask
> anyway. We're getting ready
> > to put a used Electrovert H-500 out on our floor.
> We currently have a old
> > Hollis Poly-clean. When you look at the blowers on
> a Poly-Clean compared to
> > the blowers on the H-500, the H-500's blowers look
> about twice as big...and
> > the Hollis is kinda' loud...but people don't
> complain too much when it's
> > running...I don't know about the H-500 though.
> >
> > The sound suppresion foam on the inside of the
> H-500 needs replacing, it's
> > deteriorated quite a bit. But there's a person
> here that is suggesting that
> > instead of replacing the foam, look into "white
> noise" generators. This
> > person says that when they were in a machine shop
> environment, "white noise
> > generators" were amazing as far as lowering the
> decible level of the machines.
> >
> > I have to plead ignorance on this subject. Do any
> of you have any knowledge
> > about this? Or have any first hand experience with
> "white noise generators"?
> >
> > Myself, I think we should just replace the sound
> suppression foam, but this
> > person swears that "white noise generators" is the
> way to go (but they can't
> > tell me where I can find this stuff)...if that is
> true, where do I go to get
> > these generators (speakers and certain frequency
> sources I assume)? Is there
> > such equipment? I've searched the web, but can't
> find anybody that sells this
> > stuff (makes me more confidant that I should just
> replace the sound
> > suppresion foam).
> >
> > Is this just a bunch of gobble-dee-gook or what?
> >
> > -Steve Gregory-
> >
> >
>
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