At 09:40 PM 11/21/2003, Noelslv@aol.com wrote: >In theory you can take the chip from the headsets replace the mike >(input) with one mounted centrally in the van and hook the output to a >more powerful amp with larger speakers and cancel the noise altogether >with no need to wear headsets. > >Noel >82 Westy Wavelength = propagation speed / frequency. Concert "A" 440 Hz has wavelength of a about 2.5 feet; two octaves up about 7.5 inches. For the phase cancelling to work in location X at a given frequency, the detector has to be within a small fraction of a wavelength of the suppression point. On my phones the detector is just outside the ear cavity. They generate a high-frequency hiss that's quite noticeable if music isn't playing on them -- dunno how much is electronics and how much is phase noise. And they have a specific location over my ear that works best, eighth-inch off can hear the difference. cheers d
-- David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/ '84 Westy "Dutiful Passage" '85 GL "Poor Relation" |
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