cliff wrote:
To be clear, there is no suggestion that a center hit will create greater volume, but I suspect that the off center hit creates the perception of greater volume as more different frequencies are produced. I am sure the science already exists, but the only way I could prove this theory to myself would be with a reliably constant strike source and a decibel meter, which is not fooled by tonal complexity, but instead measures real volume.
What I mean by “more fundamental” is a sound with fewer overtones. Think of the batter head as being composed of a nearly infinite number of individual ‘strings’, each with one end point at the bearing edge, the other at the point where the beater strikes the head, with each ‘string’ producing a frequency relative to it’s own unique length and tension. With that concept, it becomes clear that the way to produce the fewest tones (and harmonics thereof) is by striking in the center where all of ‘strings’ are of equal length.
Make sense?
Yes, we are on the same page on terms.
Now, as to the character and quality of the tone, I am willing to trust my senses to evaluate the way in which the strike is mixing with the kit from my vantage point as drummer, as long as reasonably schooled ears hear the same thing in the room. Scientific instruments are good for isolating empirical reality, but not so good at rendering human response. Which is why the Sonor catalogs picturing scientists in white lab coats in acoustically controlled rooms cause us to chuckle. I guess it is not so much a question of empirical evidence as it is one of perception.
In this regard, we have both looked at the remarkable video of a center struck vs. off-center struck membrane, but does that tell the entire story? Certainly where my tympani are concerned, a center hit renders a sort of hard feel and muted tonality, as Roland says. Granted, it's a round bottomed bowl rather than a contained cylinder, but the bass drum reacts the same way, to my ear.
An interesting quote from concert bass instructions (
http://www.kjos.com/band/band_news/band_news_bass.html); the "lifting" motion described corresponds to allowing the pedal complete freedom after the strike, getting the foot off even before the strike so that it can rebound cleanly and completely:
The optimum playing spot, for most occasions, is about halfway between the rim and center of the head. See the illustration below from the Standard of Excellence, Drums & Mallet Percussion Book 1, page 3 [I think we can all visualize it. ]. Playing in this manner will provide a low fundamental tone with definition. Avoid striking the drum directly in the center, because this will produce a very dead tone. Also, one should avoid striking too close to the rim, as the tone will not be deep enough. Bass drummers should be sure to always strike the drum with a lifting motion so that the sound is drawn out of the drum, rather than striking into the drumhead.
I realize this is not empirical evidence either, but I'm quoting it so I don't feel so alone with my argument.