Conference_programme: 11: Measurement techniques

Lecture: Mimicking the Sound Field of a Dodecahedral Loudspeaker by a Common Directional Loudspeaker for Reverberation Time Measurements

Author(s): Papadakis Nikolaos M., Serras Anargyros, Stavroulakis Georgios E.

Summary:
A dodecahedral loudspeaker is commonly required for precise impulse response and reverberation time measurements in acoustic spaces. Alternative methods exist for the excitation of the sound field and are useful when a dodecahedral speaker is not available. A common directional loudspeaker is utilized in this study for mimicking the sound field created by a dodecahedral loudspeaker for reverberation time measurements. For this purpose the front face of the directional loudspeaker was placed in twelve positions similar to the twelve positions of the faces of a dodecahedral loudspeaker. For each of the twelve positions with the use of an exponential sine sweep, impulse responses were measured for the same microphone position. The twelve impulse responses obtained were added up creating a single impulse response. Measurements were also performed with the use of a dodecahedral loudspeaker for the same source and microphone positions according to ISO 3382-1:2009 in spaces with volumes of 192.4 m3 and 88 m3. Comparison for octave band reverberation time measurements between those obtained with the dodecahedral loudspeaker and the proposed method for the same microphone and source positions shows a mean absolute error of 0.038 sec with a standard deviation of 0.055 sec in the case of the room with volume 192.4 m3. In the case of the room with volume 88 m3 the mean absolute error was 0.056 sec with a standard deviation of 0.077 sec. Implications of the findings suggest that reverberation time measurements with the proposed method utilizing a common directional loudspeaker can provide usable results. The proposed method appears to be an alternative low-cost method for measuring reverberation time without the use of a dodecahedral loudspeaker.\n

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Corresponding author

Name: Mr Nikolaos M. Papadakis

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Country: Greece