Re: Re: This Hertz


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Posted by Rick Denney on September 04, 2003 at 09:31:45:

In Reply to: Re: This Hertz posted by Doug on August 31, 2003 at 21:56:35:

As others have said, it's the lineup of the harmonics that makes a low note audible. I can't hear any sine wave below about 30 Hz, thought I can feel it. And even in the 30's, a sine wave is more felt than heard, and most people would describe it as a soft hum, even if it is tearing the surrounds apart on your speakers.

When you hear "clicking" sounds at very low frequencies, such as below 20 Hz, you are hearing short bursts of high harmonics repeated frequently. Making that sound like a musical note is quite a challenge, but it is those upper harmonics that even make it possible. I measured harmonic content in tuba notes in the normal range (a 58-Hz low Bb) extending from the fundamental up perhaps 12 or 15 harmonic multipliers, which is in the range of about 1000 Hz. It is the spacing of those harmonics--at 58 Hz intervals--that gives the impression of depth. Tubas and tuba players who can make efficient tones with well-tuned harmonics have lots of core to their sound in the normal range, and also have pedal tones that make discernable pitches in our heads. As Dr. Young says, the amount of fundamental in those sounds is nearly nil. As Chuck says, we can simulate that same effect by playing a note an octave higher, plus a well-tuned fifth. The fifth will fill in many of the harmonics of the pedal, and when mixed with the octave note, produces a difference tone at the lower octave. But the interval has to be tuned to itself (not to a well-tempered scale) for it to work.

We should be wary, in my opinion, of foisting our own ability to hear and produce low pitches on an unsuspecting public. Just because we have become enamored with the ability to hear and make sub-audible tones doesn't mean that the audience can go there with us. It is an effect at best, and has to be kept in that context, it seems to me. We have had threads before about those who feel the need to take everything down an octave.

Rick "who finds the musical value of pedal tones limited at best" Denney


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