Measuring reverberation time using preprocessed energy detection

The Schroeder’s backward integration method and its field of application have been widely studied in the literature; some papers analyze the performance of the method, some others suggest various enhancement techniques. Notwithstanding these findings, there exist extreme cases where the energy decay envelope may not be properly extracted using the classical backward integration method; among them the case where the signal-to-noise ratio of the measured impulse response is very low, as in the case of structural reverberation, or the case where the measured impulse response is very long with a multi-slope decay. The alternatives found in the literature range from the use of the Hilbert transform to non linear processing techniques. In the present work a method based on preprocessed energy detection is proposed. It is shown that it returns the correct envelope and permits a good evaluation of the decay even over a limited dynamic range. The use of this solution in the above mentioned critical cases is analyzed and some theoretical interpretations are advanced.