We know there is an overtone series, or harmonic series, i.e. if a note A of 440 Hz is being played on a musical instrument, there will also be different amplitudes of sound of 880 Hz (440 Hz * 2), 1320 Hz (440 Hz * 3) etc. emitted at the same time.
But will there be a series of undertones (i.e. 220 Hz, 110 Hz...) emitted too?
I'm asking this question because:
- I can sometimes hear a note which is an octave lower than what's actually being played on a piano. This can be very significant if this note is in a chord, which can even make me think it's an inversion;
- In a discussion of the mechanism of the new Taylor V-Class bracing, an explanation which was claimed to be made by Andy Powers, the designer of the bracing, seems to believe the existence of undertones;
- However, the concept "undertone" is rarely mentioned elsewhere. The wikipedia page believes undertone series can only be produced with unconventional methods.