SC-04-03 meeting, New York, 2005-10

Report of the SC-04-03 Working Group on Loudspeaker Measurement and Modelling of the SC-04 Subcommittee on Acoustics held in New York, NY., USA., 2005-10-07

The meeting was convened by chairman D. Prince.

The agenda and the report of the previous meeting on 2005-05-28 in Barcelona, Spain, were agreed as written.

Current projects

AES-1id-R: Review of AES-1id-1991 (r2003): Plane-Wave Tubes: Design and Practice
No progress to report.

AES-5id-R: Review of AES-5id-1997 (r2003): Frequency and angular resolution for measuring, presenting and predicting loudspeaker polar data
No action was requested or required.

AES2-R: Review of AES2-1984 (r2003): Specification of loudspeaker components used in professional audio and sound reinforcement
Prince reviewed the document progression and delays, and recommended releasing the doc in it's current form with request for comments by end of November with review comments to follow by the entire working group

M. Buck will remove red-lined comments from current document. The secretariat will coordinate with Buck and review the current format of the document with the intent to advance it to a PWD.

D. Keele is working on a test signal for AES power test generator for noise but needs clarification on what signals should be included. Keele demonstrated a software interface. Prince noted that, for the software to be included in a standard, it should only provide the signals defined in that standard and no others. A discussion of crest factor considered the variation of crest factor pre crossover and amplifier, compared with post crossover and amplifier, as noted in the IEC specification. Further discussion to be held on the e-mail reflector in coordination with other comments on the AES2R PWD.

R. Sauro raised some issues related to power testing and general loudspeaker testing in the new NWAA Labs facilities and will contribute to the reflector.

Development projects

AES-X103: Large Signal Parameters of Low-Frequency Loudspeaker Drivers
W. Klippel had proposed closing X103 in Barcelona in favour of an IEC doc. X103 to be (is) closed.

AES-X129: Loudspeaker Distortion Perception and Measurement
This project is being discussed by task group SC-04-03-D. S. Temme on behalf of J. Stewart reviewed the September report and highlights of the subsequent task group teleconference and discussion. Tests still need better definition before they can progress. A. Voishvillo reported on some simple tests demonstrating a lack of correlation of measurements and listening experience. Prince noted the need to work interactively with psychoacoustic testing to define what can be tested and how. D. Button noted that S. Olive was again studying non-linear efects and may participate via Button. There was still no clarity on which experiment would be most useful and how a subjective vs. objective correlation might be achieved.

The task group will continue meetings to have a first listening test proposal for the Paris meeting. Prince requested that the group provide more advance notice of teleconferences to increase participation.

New projects

Prince noted that two new proposals for standardizing non-linear terminology are submitted to the IEC and may require input from this working group since IEC TC100 has limited expertise in this area. Yonge reviewed the options that were available and suggested that the working group could support the IEC effort via the proper liaison channels, specifically the AES Category D liaison and also by individual participation through the various IEC national committees.

Klippel reviewed the scope of the proposals and encouraged participation. Prince noted that the two IEC proposals are on the standards website for review.

Mark Yonge is instructed to inform IEC that the AES SC-04-03 working group is prepared to support this project in whatever way possible.

New business

Prince noted that the SC-04-07 working group is closed and its maintenance projects will be redistributed by the SC-04 committee.

The next meeting will be held in conjunction with the AES 120th Convention in Paris, France, 2006-05

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