Accurate estimation of the mean sound pressure level in enclosures

The accurate determination of the mean sound pressure level is the basis for the determination of the sound power of a source in enclosures. The relation between the sound power of the source under investigation and the mean sound pressure level to be measured in the room can be derived either by means of wave theory or statistical room acoustics. It is shown that both models yield the same relation in the limiting case of high frequencies. Taking this relation as a starting point, it is first possible to include the modal behavior into the statistical model which is important in order to extend the validity of the statistical model to the low-frequency range. Second, the correction term for the potential energy stored near the room boundaries, which is known as the Waterhouse correction, is improved by taking into account the absorption characteristic of the room walls. The improved relation gives a higher accuracy for the determination of the mean sound pressure level in enclosures especially in the low-frequency range. Experimental data is given to verify the theoretical results. (C) 1999 Acoustical Society of America. [S0001-4966(99)01508-8].