briand@tekig1.UUCP (Brian Diehm) (06/27/84)
{} In the US, the horizontal frequency for TVs (and most non-interlaced terminals) is 15.75kHz. Yes, this is well below 20kHz. You should remember that this is a low-amplitude noise (or should be, as it is attempted to be eliminated), and therefore some people who really can hear that frequency might not detect it in an office environment. For my case (my case is aged 32), I can hear the sound, but not in any normal sense of hearing. It tightens the muscles in the back of my neck, but I can barely "hear" it at all - my hearing ability drops off about 15.5kHz. This only points out how subjective the audio field can get, I guess. Anyway, I know of one escalator in a local department store that absolutely drives me bananas, though I can't actually *hear* it. Perhaps, some of my acquaintences would say, that's why ultrasonic waves work at repelling rodents :-) ! Brian Diehm Tektronix, Inc.
hrs@houxb.UUCP (H.SILBIGER) (06/29/84)
Don't worry, by the time you are 40 you will probably not be able to hear the retrace frequency, or any other sounds at those high frequencies any more. The technical name for this progressive hearing loss with age is presbyacusis. Herman Silbiger CGE