Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10 5/3/83; site utcsrgv.UUCP
Path: utzoo!utcsrgv!mason
From: mason@utcsrgv.UUCP (Dave Mason)
Newsgroups: net.cog-eng
Subject: Re: start off with a bang -- screen colors question...
Message-ID: <2035@utcsrgv.UUCP>
Date: Sat, 20-Aug-83 05:13:17 EDT
Article-I.D.: utcsrgv.2035
Posted: Sat Aug 20 05:13:17 1983
Date-Received: Sat, 20-Aug-83 09:44:28 EDT
References: <532@pyuxhh.UUCP>
Organization: CSRG, University of Toronto
Lines: 18

The whine is from the windings in the flyback transformer. TVs do it too,
but the sound normally drowns it out. Most current terminals use TV technology
which uses a 15750Hz horizontal scan rate giving 262 (or 525 if interlaced)
raster lines. I hear it but have learned to mask it out long ago. (It can
be quite useful in a open plan office if you are the last to leave, you can
hear if everyone's terminal is switched off. Unfortunately this frequency is
a little high for the ears to figure ot the direction.)

The supervisors (and possible the salepeople) probably were older than the
average in the office and ears start rolling off high frequencies as you get
older.  We're also not used to hearing such frequencies except as harmonics
so some people may have trouble (I do sometimes) detecting this strange
sensation as sound.  The decibel level is not high (I don't) think, but I
sometimes wonder the contribution this may make to fatigue.

 -- Gandalf's flunky Hobbit --   Dave Mason, U. Toronto CSRG,
        {cornell,watmath,ihnp4,floyd,allegra,utzoo,uw-beaver}!utcsrgv!mason
     or {cwruecmp,duke,linus,lsuc,research}!utzoo!utcsrgv!mason   (UUCP)