The cymbal as a structural acoustics demonstration: From evanescence to chaos
Kent L. Gee, Scott D. Sommerfeldt, Trevor A. Stout, Tracianne B. Neilsen, Pegah Aslani · The Journal of the Acoustical Society of America · 2015
The cymbal can be used as a rich structural acoustics demonstration. Many well-defined normal modes spanning a broad range of frequencies can be evaluated using various techniques, including Chladni patterns, speckle interferometry, Doppler vibrometry, and acoustical holography. The literature shows modal patterns that are both membrane-like with nodal lines and circles as well as more complicated, irregular shapes. When the cymbal is struck forcefully, orthogonality gives way to modal coupling and resulting chaotic vibration that produces the characteristic shimmering sound. The sound radiation favors high-frequency modes; however, when the cymbal is put close to the ear, low frequencies dominate the sound heard. This low-frequency ringing persists well after the rest of the sound has decayed. This auralized evanescence will be demonstrated and further described as part of the presentation.