Abstract by Michael Rose
Physics and Astronomy
Scott Sommerfeldt, Kent Gee
Structural vibration damping of a vacuum-assisted toilet
Vacuum-assisted toilet noise can be uncomfortable. One common way to reduce noise levels is to damp structural vibrations that radiate sound. We investigated how effective constrained layer damping (CLD) treatments reduce the radiated noise level. To find the structural anti-node locations of a toilet, we excited one with a shaker and scanned the velocity response of the inside of the bowl with a 3-dimensional scanning laser Doppler vibrometer (3D SLDV). We also scanned the bowl with an accelerometer during many flush cycles. A microphone placed one meter above the bowl measured the radiated sound level. The bowl’s rim on the front vibrated the most. Structural vibrational energy concentrated around 100-400 Hz while radiated sound concentrated around 400 Hz – 2 kHz. Applying damping materials reduced structural vibrations, sometimes by 20 dB. We conclude that CLD treatments are able to reduce structural vibrations. Further results of the investigation will be shown and discussed.