Key points are not available for this paper at this time.
This paper is the second of two papers describing the transfer function method of measuring in-duct acoustic properties. In the previous paper the theoretical formulae were developed. In this paper experimental results are presented to demonstrate the accuracy and the general utility of the method. Test results of the complex reflection coefficient, the complex acoustic impedance, and the transmission loss are found to agree well with theoretical predictions. The sound absorption coefficient was evaluated with both the new method and the conventional Standing-Wave-Ratio (SWR) method and the accuracy of the two results are found to be comparable. The new method, however, is about 40 times faster than the SWR method. Also included are experimental verifications of two methods for improving the transfer function estimate, namely the use of sensor switching for automatic system calibration and the use of coherence functions for signal enhancement.
Chung et al. (Mon,) studied this question.