Subject: Re: Difference Tones From: Chen-gia TSAI <gia(at)SNAFU.DE> Date: Thu, 12 Sep 2002 22:34:23 +0800In the CD of Ernst Terhardt's book 'Akustische Kommunikation' (1998, Springer) I heard the combination tones for the fist time. There are two pure tones in the sixth track. f1=1000 Hz; f2 varies continuously from 1200 Hz to 1600 Hz, then back to 1200 Hz. I can hear the combination tones with frequencies 2*f1-f2 and f2-f1. In a similar way, I produced audible combination tones with two flutes. I played a flute tone with constant frequency f2=1500 Hz. My teacher played a lower flute tone whose frequency f1 varied continuously from 1281 Hz to 1150 Hz, then back to 1281 Hz. The difference tone f2-f1 was audible. The flute is optimal for this experiment in that the pitch can be modified by varying the blowing angle. Chen-Gia Tsai gia(at)snafu.de