Developments to Watch
WILL SERENITY COME TO THE FACTORY FLOOR?
NEXT TIME YOU'RE FEELING deafened and defeated by a noisy vacuum cleaner or refrigerator, ponder the gongs of Korean temple bells. These huge, barrel-shaped wonders vibrate much like the cylindrical metal casings on noisy machinery such as refrigeration and heat pump compressors. By understanding how the bells produce their deep sounds, Purdue University engineering professor Werner Soedel thinks he can reduce mechanical racket.
To fathom the bells, Soedel created a simplified mathematical model, described in the June issue of the Journal of Sound & Vibration. His formulas suggest that the bells' rhythmic resonance comes from the uneven distribution of ornamental carvings on the bells' exterior. Just a slight deviation from axial symmetry creates the beating effect that pleases the ear in a mountain retreat but can cause hearing disorders on the factory floor. By aiding a more even distribution of mass in machinery casings, Soedel's formulas could reduce the noise--and maybe resolve a modern koan: What causes the sound of one compressor clanging....EDITED BY PETER COY