Tone library generates inaccurate beat frequencies

[palazzol]

The Tone library uses ints (in Hz) to represent frequencies to generate. The original Altman program uses fractional beat frequencies like 2.2Hz. Even though the table contains accurate floating point values for the beat frequencies, the best the current Tone library can do is round to the nearest whole number beat frequency, in Hz.

I implemented a fork which uses raw timers to get around this issue:
https://github.com/palazzol/Arduino-Brain-Machine