GOLDBERG AND MÄKIVIRTA
AUTOMATED IN-SITU EQUALISATION
AES 23RD CONFERENCE, May 23-25, 2003
11
rections to the response by equalisation a very chal-
lenging task. Secondly, the three-way systems contain
more room response controls than the two-way sys-
tems, which gives a higher capability for the equaliser
to compensate for room problems. It should also be
noted that the type of equalisation the room response
controls are designed for is a gentle shaping of the re-
sponse. High order narrow band corrections are not
possible, therefore the characteristics of the room and
the quality of its acoustical design will play a major
role.
6. CONCLUSIONS
The low-order room response adjustment filters in ac-
tive loudspeakers can significantly improve the per-
ceived quality of audio reproduction. The automated
optimisation algorithm presented in this paper is used
to select the optimal combination of settings for loud-
speakers where the room response equaliser is imple-
mented as a filter set with discrete parameter values.
The algorithm proves to be useful because it performs
systematically with widely varying types of loud-
speakers, with slightly differing filter sets and loud-
speakers found in multiple types of 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 filters, and performs
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 Development) and Genelec
Oy. Parts of this work are presented in more detail as
an MSc Thesis at the Helsinki University of Technol-
ogy [41].
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