Physics of Sound?

[DrummerCafe]

Sorry, I didn't know what to call this thread, so I tried to come up with something that would definitely get you all to at least read my initial post! LOL

 

While I was at PASIC, I was talking with Roy Burns from Aquarian Drumheads about some of Aquarian's new products. During our visit, Roy mentioned that Aquarian had been doing some research and found that the overall sound of a drum is 70% from the drumhead, meaning the type of drumhead you use will determine over two-thirds of the sound you will get from a drum.

 

What do you think of this? Do you agree, disagree or are you uncertain at this time? Please give some evidence to support your claim. Yes, that means you too Felix.

 

I personally am still pondering this bit of information and have strategically avoided making comments until after a few others post theirs! LOL

[Jazzman]

Clever...........Bart, did you ever hear of African drums that look like a skin in a frame? No drum perse, but can get a loud sound when hit. The sound is based on the size of the heads only,(but there is a limit to the low end). The sound of these drums disapate the sound just beyond the head. The sound is louder in a closed room than if it were played outside for instance. I think that answers one question.

 

My theory and deductions:

 

I believe that the bottom head on a drum, fine tunes the main head, not allowing the main head to deflect as much( thats's why we can make adjustments to the bottom head with a key. The small hole in the side of the drum allows air to leave, allowing the sound to take place, the bottom head now can react to the hit. This bottom head in turn gives better control of a roll and general action back to the stick. Or this, "For every action in one direction there is an equal and opposite reaction". When the top head is compressed with a hit of the stick, the bottom head acts like a big spring to pop the top head back into position for another hit.

 

If you take the bottom head off, the drum acts like a meg-a-phone and is louder, with less action for the stick. You would have to tune the top head up to receive the same action to the stick. The longer the tube of the drum the lower and louder the sound pressure level can get.

 

Look at steel drums when played, the longer the drum is the the more bass sound is present. The shorter the steel drum in (tube length) the higher pitched the drum is.

 

I guess I have to agree that the head on a regular drum set is at least 70% of the drum. But in the case of the African drums 100%, and in the case of steel drums < 70%.

 

My take, am I wrong?.......stay cool......back to-ya.

 

Jazzman

[Scream187]

well first of all I got no clue what I'm talking about.

 

That said, I think its probably right, well I dunno maybe what I'm gonna said is foolish but if you take a head and put it on anything that has the shape of a cylander, its gonna sound like a drum, maybe not a great one but still... but if you take a piece of somewhatever shit u can find and put it on a drum its not gonna sound like a drum... My english really sucks so I hope you get what I mean, even if its completly false, its late here and as I said I got no clue what I'm talking about!

 

o yea, for a snare I dont think its 70%, theres also that thing I dont know what its called under it that is an important part of the sound. But for the other drums yea I guess the head are probably 70% of the sound.

[felix stein]

I'd say the harder one plays the more the shell tone is dominant as opposed to playing softer- then the head would have a greater part in determining decay tone and pitch.

 

Shells have alot to do with the timbre of the initial "cut" or what I call the fundamental. And I think different heads help or hinder this phenomenon.

 

Is a drum head 70% of your sound? Yeah, when you are a soft playing jazz cat I'd say it's true. And if one were to just listen to a head without a shell (ie roto tom/arbiter drums)one would hear 100% of the head...put it on a drum...Ok, the drum will project more and have a richer tone...and I would say roy's assumption of 70% is a good one from my drum tuning experience.

[sidereal]

Vamping off what felix said...

 

I don't see how one can make a blanket statement that the head is responsible for 70 percent of the sound. I don't know what I'm talking about either but I'd imagine the drum head is a variable in this equation, whose effect is dependent on other factors. I think the head might be more or less of a factor in the sound depending on the velocity of the stroke (as felix said), the tension of the tuning, whether there is any free-floating mounting system (like RIMS), and the wood itself. I'd say if you consider the head within the context of those elements above, that "70 percent of the sound" thing moves around the percentage scale quite a bit.

 

For example, does the head account for the same 70 percent of the sound when the drum is a thicker ply shell? Maybe a thicker shell accounts for more of the sound you perceive than a thinner shell does?

 

I don't know the answers to these questions, but it's interesting to think about.

 

Another thing... I think if you put a Remo on a Roto Tom and an Aquarian on a Roto Tom, it still sounds like a Roto Tom. So again, interesting idea... but I'm not buying it.

[agogobil]

There's quite a difference in the sound from Peavey shells, and fiberglass as compared to wood shells ...

 

There's so much going on with the physics ... it's all a combination of things - stick size and shape, shell composition and thickness, how the drum is struck ... I'd say it's 50/10/10/10/10/10 - 50% being the heads ... so much involved.

 

But then again, I'm no physicist or drumhead manufacturer ... use yer ears, fercryinoutloud!

------------------------

 

"If you ask me a question I don't know, I'm not going to answer." - Yogi B.

[DrummerCafe]

All very interesting indeed. I too am no drumhead manufacture, physicist or professor of sound, so I don't know much of what I'm talking about either. I have a deep interest in the topic and have devoted a good number of hours over the years studying the like.

 

My deduction would be that whether it be 70% or 50%, the drumhead contributes at least half of the sound that we perceive when a drum is struck. All you have to do is hit a drum shell with no drumheads and see what kind of sound you get! We know that the drum's shell material, bearing edges, number of plys (if wood), diameter, depth, rims, lugs, snares (if it's a snare drum), and the air inside the drum all play a role in the sound of a drum and how it reacts to the drumheads when struck. This obviously is not taking into account the type of drumstick being used and the way the drum is being struck.

 

Although Roy Burns did not site his sources, I do know that Aquarian has been doing some research on the topic. It would be interesting to read some scientific findings on this, so I'll see what I can find. I know I have read a number of articles over the years in the Percussive Notes publications. Percussive Notes is the periodical put out by the Percussive Arts Society .

 

I think there is one thing that we all seem to agree on, regardless of what the scientific reports say and as simplistic as it may seem, the drumhead is the dominant portion of a drum's sound.