Report of the SC-04-03 Working Group on Loudspeaker Measurement and Modeling of the SC-04 Subcommittee on Acoustics, held in conjunction with the AES 116th Convention in Berlin, Germany, 2004-05-09

The meeting was convened by vice-chair N. Harris.

The agenda and the report of the previous meeting were accepted as written.

Open Projects

AES-1ID-R, Review of AES-1id-1991 (r2003): Plane-Wave Tubes: Design and Practice
M. Buck observed that the high-frequency limit is influenced by the relative position of the microphone position within the tube. D. Button advocated using the average of a number of mic positions.

Buck summarised that more work was required. A further draft is anticipated at the next meeting.

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

AES2-R, Review of AES2-1984 (r2003): Specification of loudspeaker components used in professional audio and sound reinforcement
Buck had met with J. Woodgate and proposed that the simple version, previously discussed, be released in time for the AES 117th Convention and a full revision in 18 months.

Development Projects

AES-X72, Acoustic Center of Loudspeakers
W. Anhert noted that it had been agreed to drop the phrase "Acoustic center". Olson had sent graphics documents to D. Prince and volunteered with Anhert to help Prince develop the document for completion.

AES-X103, Large Signal Parameters of Low-Frequency Loudspeaker Drivers
D. Field reported on the ALMA meeting to discuss Xmax. There was not a lot of support to change the existing definition. Xmech was discussed but will require a clear measurement and a calculated result. He also talked of a single figure of merit but doubted that the parameter B(subX,L,C) was a satisfactory candidate. Field will follow up with an ALMA draft for the next meeting in October.

AES-X129, Loudspeaker Distortion Perception and Measurement
This project is being developed by task group SC-04-03-D.

A very successful workshop was led by J.S. Stewart. His results indicate that development is in right direction. Button was impressed with the correlation. M. Keyhl wants to study the matter more closely.

G. Soulodre from Communications Research Centre, Ottawa (CRC) is working on difference perception and is planning to do subjective testing in the same area as AES-X129. They still need to identify the test path and the listener demographic to take into account, for example, listener experience. Soulodre requested loudspeaker models to run tests with.

Stewart reminded the meeting that some distortion metrics do not align with some perception. There was substantial discussion on valuable metrics and how to assess them. Button observed that although there were no models, perhaps binaural recordings at different levels could suffice, using equalisation to compensate for frequency response distortions. For excursion related distortion models, the work of W. Klippel is available and A. Voishvillo has compression driver models but which may need to be modified for tweeters.

Liaisons

ALMA - The International Loudspeaker Association (see above)

New Projects

There were no new projects.

New Business

There was no new business.

The next meeting will be held in conjunction with the AES 117th Convention in San Francisco, CA., US., 2004-10.