Kill drum head overtones without anything touching the drum head!

[calvinrose]

TL;DR Summary

Application of acoustical resistance: You don't need to attach foam or tape to your drum heads to kill or lessen the overtones.

Hi All, I considered filing a patent for this invention, but instead decided to publish it so people could use it to advance the state-of-the-art in drums.

You don't need to add tape or pillows to your drum heads to muffle the overtones. Using tape or pillows also kills the strike of the stick or pedal and kills the fundamental tone of the drum head.

All you need to do is attach some OPEN CELL FOAM (not closed cell!) on the inside of your drum rims about 1/8" away from the drum head (no need for the foam to touch the drum head!). The thicker the open cell foam, the more the overtones will be muted. 1" thick open cell foam should work pretty well, but experiment with it.

I've attached a picture from the patent application I didn't file so you can see how this might be applied. The distance "d" in the picture should be about 1/8" to be effective. You can make the open cell foam go all the way around the rim if you like instead of just in 4 places as shown in the picture.

Two of the benefits of this method (beside the fact that it's cool ) is 1) It allows the impact of the drum stick or bass pedal mallet to not be attenuated in any way; and 2) It kills the overtones without dampening the fundamental tone of the drum head.

If you want to convince yourself this works without taking your drums apart, just take a microphone Pop Filter like the one shown in the image below and place it about 1/8" to 1/4" above an un-muted drum head.

 

[anorlunda]

Congratulations. I think that is clever.

But to a non-musician, please explain why removing overtones is desirable. The quality of sounds of many instruments (as distinct from a tone generator) is the overtones.

 

[calvinrose]

Thank you!

Overtones as you know aren't harmonics, so they don't sound very good. In fact they beat against each other making the tone even worse. I tried to attach a file with a naked drum head (full overtones) and one that is partially dampened using the technique I described, but this site won't let me upload sound files. Here are links to the two files: First the naked drum head:

Second, the slightly damped drum head using the technique I described:

 

[Dale]

Do you think this approach is specific to drums, or could it be adapted for other instruments as well?

 

[anorlunda]

Overtones as you know aren't harmonics

Educate me. The dictionary says that an overtone is a harmonic. So how do you define overtone?

Give me numbers, If the fundamental is 440 Hertz, the first harmonic is 880, what frequency is an overtone?

 

[calvinrose]

Do you think this approach is specific to drums, or could it be adapted for other instruments as well?

I know the decay time of a vibraphone changes when you add or remove the tubes under the bars. I never modeled why, but would guess it's more complicated than just adding or subtracting acoustical resistance.

 

[calvinrose]

Educate me. The dictionary says that an overtone is a harmonic. So how do you define overtone?

Give me numbers, If the fundamental is 440 Hertz, the first harmonic is 880, what frequency is an overtone?

Harmonics are integer multiples of the fundamental while Overtones are not necessarily integer multiples. Harmonics = Overtones, but Overtones are not necessarily Harmonics. So in your example 880 Hz is both an Overtone and a Harmonic of 440 Hz, but 1,000 Hz is an Overtone of 440 Hz, but not a Harmonic.

 

[Tom.G]

I seem to recall that there are many vibration modes in a diaphragm, not all being harmonics, and somewhat dependent on where the diaphragm is excited.

 

[calvinrose]

The picture of drum head overtones was taken from the following reference: http://circularscience.com/about-drums

It paints a pretty ugly picture of how a drum head sounds without dampening the overtones. Just try and play all those notes on a piano and see how it sounds.

 

[Dale]

What does "lug note" mean?

 

[calvinrose]

I've never heard that term before, but the way it is used in the article I referenced at http://circularscience.com/about-drums it means the first overtone where the drum head vibrates in half