Re: Burroughs, Strobes (was Re: monitor refresh rates & epilepsy)


Subject: Re: Burroughs, Strobes (was Re: monitor refresh rates & epilepsy)
From: Richard Wentk (richard@skydancer.com)
Date: Mon Jan 17 2005 - 21:09:15 EST


At 23:12 17/01/2005, you wrote:

>i must be unusual then... i see strobes at 60 - 75Hz...

Depends what you mean by 'see' and 'strobes'. Anyone who waves their hand
in front of a CRT refreshing at 90Hz will see a strobing effect. But it's
very rare to experience 60Hz refresh as continuous extreme strobing of the
sort you get at lower rates from a strobe light.

One reason is that a CRT isn't really strobing at all, in the sense of the
picture being switched full on and then followed by full off.

The other is that 70Hz is way faster than anything the brain can process as
discrete chunks. Visually it's a very similar effect to the one where above
a certain frequency, a clickstream is perceived as a continuous tone.

>then again, i hear whistles on tv sets when they're on stand-by.... and i
>can hear high frequencies above average...

It's been a while since I've been anywhere near a TV, so I have no idea if
this is true for me or not.

I can hear different noiseshaping types quite clearly. Most of those have
different kinds of mush in the very high treble, but what I'm listening for
is something different to that.

Richard



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