Preferred Number - Music

Music

While some instruments (trombone, theremin, etc.) can play a tone at any arbitrary frequency, other instruments (such as pianos) can only play a limited set of tones. The very popular "twelve-tone equal temperament" selects tones from the geometric sequence

where k is typically 440 Hz, though other standards have been used. However, other less common tuning systems have also been historically important as preferred audio frequencies.

Since 210≈103, 21/12≈103/120=101/40, and the resultant frequency spacing is very similar to the R40 series.