Google "Taos Hum". It might be related. The hypothesis that I have reached is that the noise does not exist at its perceived frequency. Rather, it is similar to "intermodulation" in a radio receiver... the product of mixing two or more signals. It is very real to those who hear it but totally undetectable to those who cannot. There is a local condition here that some find annoying and others cannot detect it. It is neither constant or the same intensity in the affected area. I cannot hear it but it has been described as similar to the sound made by the Star Wars Light Sabers. Since we have been in the low sunspot activity, I have not been made aware of the condition. Of course one must consider that inquiring about such things does raise a few eyebrows. John Ferrell W8CCW "My Competition is not my enemy" http://DixieNC.US ----- Original Message ----- From: "Jinx" To: "pic microcontroller discussion list" Sent: Tuesday, September 05, 2006 11:46 PM Subject: [OT] Transmission tower noise >A friend has been giving me grief for some few weeks about > noise she says is coming from a microwave tower about 300m > from her home and keeping her awake in the quiet of the night. > She describes the sound as a constant high-pitched tone. I have > every reason to believe she is not crazy, and she assures me she > has not got tinnitus or any other hearing problems. She may be > dwelling on the problem (though she says she isn't), which might > tend to aggravate any auto-suggestion. I'm getting all this from a > woman who is quite frazzled and cranky after many sleepless night > but who hasn't lost the plot. She's still quite rational about possible > causes, but not being technical at all she has a limited number of > causes to think about. There aren't many houses around where this > tower was put up so she hasn't neighbours to discuss it with > > She reckons she's being fobbed off or stonewalled by the owner > of the tower (BCL) and the local council and as she doesn't seem > to be getting anywhere on her own I've offered to try and gather > evidence. Including, if I have to, trying to record the noise to > present to someone as hard evidence. What she has so far are > just opinion and supposition. > > I haven't heard the noise myself, she's quite some distance away > and a visit hasn't been possible yet. She said a tech, ISTR, had > suggested (I don't know the circumstances or context of the > conversation) it was 15kHz, which made me think perhaps a > switch-mode with something loose, but the tone she sung over the > phone is nowhere near 15kHz. Probably more like 3/4 the way up > a piano, definitely within almost everyone's hearing range, which > you'd think would be easily heard by anyone. A late-shift engineer > came to her home and thought he kind of heard something, but > seems not in the "my god, how do you sleep with that racket ?" > league or a problem would have been immediately apparent > > If the tower is in fact putting out this mysterious tone, I wonder > about a couple of things > > (1) Apparently the sound is no louder at the tower. I would have > thought it would be, given the sqrt law unless - > > (2) there is some beat frequency being created at her home by > two or more inaudible frequencies, and she just happens to lucky > enough to be at a place where a combination of beat frequency > and distance make a node > > Any thoughts ? Any similar experiences ? > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist