Sound-absorbing and insulating enclosures for ultrasonic range

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Authors

  • Andrzej DOBRUCKI Wrocław University of Technology, Institute of Telecommunications, Teleinformatics and Acoustics
  • Bronisław ŻÓŁTOGÓRSKI Wrocław University of Technology, Institute of Telecommunications, Teleinformatics and Acoustics
  • Piotr PRUCHNICKI Wrocław University of Technology, Institute of Telecommunications, Teleinformatics and Acoustics
  • Romuald BOLEJKO Wrocław University of Technology, Institute of Telecommunications, Teleinformatics and Acoustics

Abstract

The physical phenomena occurring in sound-absorbing and insulating enclosures are subject of the present paper. These phenomena are: absorption in air and by the sound-absorbing material covering the walls and the coincidence effect. The absorption in the air can be neglected in small size enclosures for low ultrasonic frequencies (20-30 kHz). The coincidence plays a role in decrease of the sound insulation, however the main role play the leaks. The boards made of ceramic fibers have been chosen as the optimal sound-absorbing material. They are dense and have deeply porous structures. The enclosure for insulation of 20-kHz noise produced by a welding machine has been designed and manufactured, and reductions of 25 dB of peak and Leq levels have been achieved.

Keywords:

ultrasonic noise, sound absorbing and insulating enclosure, welder

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