Theory/Acoustics Question

[NinjaGeek]

Today in one of my classes, we learned about a phenomena where if you play a note and a perfect 5th above that note at the same time, you will also hear a note an octave below the original note, even though it doesn't exist.

Reason being, is because for example if you had a sound with a frequency of 220 and a sound with a frequency of 330, these would be the overtones generated by a sound of 110, and since they're also generating 110 beats per second, you're mind fills in the 110 frequency sound.

He called this concept Fundamental Bass, but upon trying to look up more info on it, I found out Fundamental Bass is used to describe the root note of a chord. Is this a term for 2 things, or did my professor just mix some terms up?

Also as a side note, does anyone know if this phenomena comes into play when playing power chords on an electric guitar? I think the professor mentioned it working best on horn-type instruments, but just wondering if this effect comes into play somewhat on electric guitar.

 

[genocide roach]

thats an interesting theory. id love to read more.

harmonics are common in sound, and in other places like EM energy. but ive never heard of a harmonic being below the root note.

one way to find out for sure is to mic a guitar and run the signal into a spectrum analyzer.
~gR~

 

[NinjaGeek]

thats an interesting theory. id love to read more.

harmonics are common in sound, and in other places like EM energy. but ive never heard of a harmonic being below the root note.

one way to find out for sure is to mic a guitar and run the signal into a spectrum analyzer.
~gR~

I meant theory in that it pertains to music theory, however it's more than a theory and use in composition all the time.

My teacher had a synthesizer play us a note at 220, then a note at 330, then both at the same time, and together was much deeper sounding, he threw in 110, and it sounded roughly the same. However on the spectrum analyzer there was no 110 note, it's purely our brain imagining the sound, but you hear it just as clearly as if it was actually there.

The effect isn't as strong because of the timbre of an instrument, but with certain ones, it is noticeable enough, and if you were limited to composing with certain instruments, and didn't have any type of bass instruments, you might use this technique to be able to hit some lower notes.

 

[PhilDemmel'sSaliva]

It happens because of the presence of nonlinear resonance in the
ear. Apparently. So anyway, when two pitches are sounded, a third lower one resounds as well. Science! Ick...

It happens on violins. Apparently that's how violinist/composer Tartini came to notice it...so knowing it occurs on at least one stringed instrument is good! Not too sure about guitar though. I'll see! I haven't paid much attention to it before, but I'll let you know if I find out.

 

[BlackMetalWhiteGuy]

I tried it on my keyboard with the standard piano patch and can just barely make out the phantom note. The lower you play it, the more apparent it gets, but I probably never would have noticed on my own.

 

[devilfish063]

Also as a side note, does anyone know if this phenomena comes into play when playing power chords on an electric guitar? I think the professor mentioned it working best on horn-type instruments, but just wondering if this effect comes into play somewhat on electric guitar.

I don't know almost anything about music theory so this probably isn't related to what you are saying but there is a simple way of getting the low power chords on a 7 string guitar sound very close with a 6 string guitar. Let's say you want the first power chord on a 7 string guitar(B on the B string and F# on the E string). You can get a similar deep power chord by playing the F# on the E string and B on the A string.
It sounds much deeper than playing the B power chord an octave up.