On 2013-01-27, David Taylor <david-tay...@blueyonder.co.uk.invalid> wrote: > On 27/01/2013 19:33, unruh wrote: >> On 2013-01-27, no-...@no-place.org <no-...@no-place.org> wrote: > [] >>> In case you are wondering, my app is a professional piano tuning app. >>> The standard in this industry is that tuning devices should be >>> accurate to 12 parts per million. I know that is probably overkill >>> for tuning pianos, but that is what the professionals expect from >>> their equipment. >> >> Ah. I would expect 1 cent, which is more like 500PPM. > > 1% (10,000 ppm) is a 4.4 cycles per second beat at 440 Hz! Completely > unacceptable. You want an imperceptible beat, ideally, well under 1 Hz. > Agreed that 12 ppm is overkill.
I agree that 1% is pretty bad-- that is 1/6 of a semitone, which is clealy preceptible. However 1 cent, 1/100 of a semitone, is the limit of audibility, and it is VERY hard to tune a piano string to 1 cent (pin slippage and adjustment, frequency coupling between the various strings which play the same note, anharmonicity of the string)-- it is not even clear what that means for the above reasons. 1 cent (NOT 1 percent-- a cent is 1/100 of a semitone) is about 1.0006 frequency ratio (.06%). _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
