Re: Jacob's Ladder "Snap" (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 18 Dec 2003 07:19:47 -0800
From: Jim Lux <jimlux@xxxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Jacob's Ladder "Snap" (fwd)

> >
> > Yes, it's possible to a have a very short impulse noise that doesn't
> > sound
> > loud, but actually is. Yes, one could damage one's hearing if one was
> > subjected to enough of them.
>
> This runs contrary to what OSHA says about hearing & exposure.

OSHA provides "guidelines" and "regulations" which can be objectively
measured and enforced and are "reasonably" easy to understand.

> Can you cite a reference, or is this your opinion?
Consider shock waves, etc.
Consider a very large pressure pulse of enough amplitude to rupture your ear
drum. Reference: Glassman, The Effects of Nuclear Weapons, 1962.

The point is that "single events" can damage hearing and that "single
events" might not sound as "loud" as they actually are, because of the
limited response speed of the mechanics and neurons.



>
> > If you're going to be working around loud noises much, invest the $200
> > in a
> > decent set of level limiting hearing protectors from, for instance,
> > Peltor.   They have microphones that pass the sound through at full
> > volume
> > (or amplified, quite handy for hearing that evil corona hiss), but
> > clamp it
> > to a safe level.  Very, very nice for working with things that go
> > suddenly
> > "bang".
>
> How do you know they are fast enough?  What's wrong with simple hearing
> protectors?

Nothing's wrong with simple hearing protectors.. they work great.  The
amplified ones are much better because you can hear all the little things
going on (switches flipping, solenoid valves actuating, people talking,
hissing of corona, etc.) until the big bang hits.  There's a lot of auditory
cues that we take for granted, and for which, in prototype/garage built
equipment, there isn't an equivalent visual cue (i.e. telltale indicator
lights for switch states, etc.)

As to response time.. microseconds, presumably, and more to the point, the
amplifiers driving the speakers are clamped to a level which isn't loud
enough to cause damage, so even if the fast acting switch failed, etc.

Granted, with a large pressure pulse (nearby explosions), the hearing
protectors probably won't help enough, but, for run of the mill working
around snaps, crackles, pops, and buzz (tesla coils, Marx, pulse discharge
stuff), they're great.
>