rcc@imsvax.UUCP (06/26/84)
Oh, the pain... Does anyone know what frequencies terminals tend to "hum" at? I work in an environment with a lot of vt100 and televideo 950 terminals and the high-frequency hum they put out gets to be incredibly painful. I've been told that the hum is *below* 20 kHz, yet most of the people in the office can't hear the hum at all (even the ones who are 26 or so). If someone out in net-land could point me at me at some references, I'd be grateful. Relevance to net.audio: Can some of you who argue about high-frequency response even *hear* the high-frequencies? -- The preceding message was brought to you by -- Ray Chen UUCP: umcp-cs!eneevax!imsvax!rcc
sunny@sun.uucp (Sunny Kirsten) (06/29/84)
Try 15750Hz, the standard video frequency...Yes, I can hear it (age 34) and
it drives me crazy. Some advanced high resolution monitors/video generators
operate at higher frequencies, up to around 35KHz, where you will neither be
bothered, nor hear. You will also note that many of the switching power
supplies being incorporated into mondern computer equipment oscillate in the
15KHz to 20KHz range.
Psychoacoustic studies have shown that frequencies right around 19KHz are real
good at stimulating an "irratibility" factor in humans, and at high enough
intensities will actually drive people to violence.
Sunny
(C) 1984, all rights reserved, except non-profit copies which include this
copyright notice. Opinions are the authors', not Sun Microsystems'.
{ucbvax|decvax|ihnp4}!sun!sunny (Sunny Kirsten of Sun Microsystems)cuda@ihuxf.UUCP (cuda) (06/29/84)
It depends on the number of horizontal lines it has to draw to get from the top of the screen to the bottom. Most run between 15 - 16 kHz. Mike Nelson AT&T Bell Labs
wmartin@brl-tgr.ARPA (Will Martin ) (07/02/84)
It is amazing that this discussion should arise just when it did; the May, 1984, issue of "db, The Sound Engineering Magazine", which just came out (it's always behind the cover date), has a long "letter to the editor" on this very subject, with lots of detailed measurements and a discussion of how the grunge audio emitted by CRT monitors in studios is probably feeding back through open mikes and consoles to distort and intermod with recorded sound. The letter is by an "R. H. Coddington", and can be found on pages 2 & 4 of the May 84 db. I strongly suggest anyone interested in this subject stop by their library and look at this; it's far too long to type in and submit to the net. Will