Proceedings of the Institute of Acoustics
ondly, three-way systems have more room response controls than two-way systems, with a higher
capability to compensate for room problems. The type of equalisation the room response controls
are designed for is a gentle shaping of the response. High order narrow band corrections are not
possible, and therefore room characteristics and the quality of its acoustical design will always play
a major role.
6 CONCLUSIONS
The low-order room response adjustment filters in active loudspeakers can significantly improve the
perceived quality of audio reproduction. The automated optimisation algorithm presented in this pa-
per is used to select an optimal combination of filter settings in loudspeakers where a room re-
sponse equaliser is implemented as a filter having discrete-valued settings. The algorithm proves to
be useful because it performs systematically with varying types of loudspeakers, with differing filter
sets in multiple types of acoustical installations. The efficiency and reliability of the algorithm has
been achieved by exploiting heuristics of experienced sound system calibration engineers. The
automated methodology obtains systematically and consistently the best combination of available
filter settings, performing quickly irrespective of the operator. The algorithm has been implemented
in a loudspeaker calibration tool used by specialists who set up and tune studios and listening
rooms.
7 ACKNOWLEDGEMENTS
The authors would like to thank Mr. Steve Fisher (SCV London) for the original inspirational idea
and some of the measurements used in the statistical analysis, Mr. Olli Salmensaari (Finnish
Broadcasting Corporation) for additional measurements, Mr. Lars Morset (Morset Sound Develop-
ment) and Genelec Oy. Parts of this work are presented in more detail as an MSc Thesis at the
Helsinki University of Technology
42
.
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