Chris Jasinski –
University of Hartford
200 Bloomfield Ave
West Hartford, CT 06117

Popular version of paper 3pMUa4
Presented Wednesday afternoon, December 09, 2020
179th ASA Meeting, Acoustics Virtually Everywhere

For many years, 3D printing (or additive manufacturing) has been a growing field with applications ranging from desktop trinkets to prototypes for replacements of human organs. Now, Klapel Percussion Instruments has designed its first line of 3D-printed snare drums.

Snare drums are commonly used in drum sets, orchestras, and marching bands. They are traditionally made with wood or metal shells, metal rims, plastic (mylar) skins, and metal connective hardware including bolts, lugs, and fasteners. For the first phase of Klapel prototypes, the shell and rim are replaced with a proprietary carbon fiber composite. Future iterations intend to replace all of the hardware with 3D printing as well.  The shell and rim are produced layer by layer until the final shape is formed. Even with high quality printers, layers can be seen in the final texture of 3D-printed objects. These layers appear as horizontal lines and vertical seams where each layer starts and finishes.

Snare drums

3D-printed snare drum and detail of finished texture.

Klapel Percussion Instruments contacted the University of Hartford Acoustics Program to assess if having a 3D-printing shell and rim changes the fundamental vibrational and acoustical characteristics of the drum. To test this, undergraduate students developed a repeatable drum striking device. The machine relies on gravity and a nearly zero-friction bearing to strike a snare drum from a consistent height above the playing surface. With precise striking force, the resulting sound produced by the drum was recorded in the University of Hartford’s anechoic chamber (a laboratory designed to eliminate all sound reflections or ‘echoes’, shown in the example photo of the striking machine). The recordings were then analyzed for their frequency content.

Snare drums

Snare drum striking machine inside Paul S. Veneklasen Research Foundation Anechoic Chamber at University of Hartford.

Along with the acoustical testing, the drum shell (the largest single component of a snare drum) underwent ‘modal analysis’, where 30 points are marked on each shell and struck with a calibrated force-sensing hammer. The resulting vibration of the drum is measured with an accelerometer. The fundamental shapes (or ‘modes’) of vibration can then be visualized using processing software.

Snare drums

Vibrational mode shapes for maple drum shell [left] and 3D-printed shell [right].

Ultimately, the vibrational and acoustical analysis resulted in the same conclusions. The fundamental shapes of vibration and the primary frequency content of the snare drum is unaffected by the process of 3D printing. The most prominent audible frequencies and vibrational shapes are identical in both the maple wood shell and the carbon fiber 3D-printed shell, as seen in the visualized modes of vibration. This means that the 3D-printed drum technology is a viable alternative to more traditional manufacturing techniques for drums.

There are substantial, measurable variations that impact the more subtle characteristics of the drum at higher, less prominent frequencies, and for more complex vibration shapes. These are noticeable above 1000 Hz in the frequency analysis comparison.

Snare drums

Frequency analysis at two striking locations for maple (wood) and carbon fiber (3D-printed) drum.

Future testing, including subjective listening tests, will aim to identify how these smaller variations impact listeners and performers. The results of the future tests can help determine how acoustical metrics can predict listener impressions.

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