Atmospheric Absorption of Sound: A Resonance Tube Apparatus for Absorption Measurements.

摘要

The bulk acoustic absorption coefficient has been measured in pure nitrogen gas using a stainless steel cylindrical resonance tube at pressures between 1to 100atm and temperatures between 20to 200C with various moisture contents. The boundary layer loss in the apparatus,which was measured to be within 2per cent of the theoretical prediction,tends to dominate the total absorption measured in nitrogen with this apparatus. Improved acoustic impedance match between the gas and the cylindrical wall also contributes significantly to the inherent sound absorption of the apparatus at high pressures.