Yes, IM Distortion can create artifacts lower in pitch than either of two or more fundamental frequencies. But other than that there's no such thing as subharmonics. Whatever the lowest frequency is for a single note, that is the fundamental.
--Ethan
Sounds logical.
There is another source of low frequencies - one which necessitates response practically to DC.
It is the brass/wind instruments - basically, a trumpet ( as the most typical of the family ) is basically a valve in which you blow and "regulate" the "output " (sound) by releasing valves with your fingers. It can generate mostly overpressure - only the most versed jazz players know how to "suck" instead of "blow" the trumpet.
Here we stumble upon yet another myth - the absolute phase. The above mentioned brass instruments will produce mostly only overpressure - giving a correspondingly output at the output of a correctly wired microphone mostly in the positive direction. It can be viewed as a sine wave superimposed on a very near to DC component. It is what gives the distinction of a trumpet from close range - and far away, say military barracks. Air tends to return to its state of equilibrioum, the further the sound has to travel, the more will be this low-next-to-DC component filtered out. This does give the sense of depth - which is sadly missing in audio equipment incapable of DC or near DC low frequency extension.
A trumpet (or any other brass or to a lesser degree, wind instrument ) will sound odd if amplified by a microphone/microphone preamp with the absolute phase inverted. NO equalization can compensate for this - absolute polarity has to be observed from input to output, if fidelity of the real sound is to be preserved.
I expect quite a hoolaballo after the above statement, with numerous "proofs" by tons of distinguished members of the audio community, who claim absolute phase to be inaudible. Yes, I agree ; in a multimiked recording, played over multi unit /way loudspeakers with phase incoherent crossoversa, it does not matter in the slightest; the inherent deficiences in recording itself render such precision impossible, and it is repeated on the multi way speakers, giving a totally predictable 50:50 outcome in the statistics of blind testing - falsely proving that absolute phase does not matter.
Try a binaural recording on good, preferably electrostatic headphones, preferably driven by high voltage DC amp ( like Stax models ) - THAT is a different ballgame altogether. The trumpet will really suck if reproduced "sucking" instead of "blowing" - and equipment lacking LF extension will be ruthlessly exposed as such.
There is more to the frequency response than just the fundamental frequencies as generally accepted. Organ, which is generally accepted to produce the lowest fundamentals ( usually 16 Hz, but there are exceptional instruments going yet one octave lower, down to 8.xy Hz ) , can be exceeded in LF extension by incomparably smaller trumpet, saxophone, etc - depending how close to these brass instruments is the listener.
I thought the fundamental, by definition, was the lowest number. Or are subharmonics really the fundamental, and the tuned frequency is ..?
