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 115th Convention in New York, NY US, 2003-10-12

The meeting was convened by chair D. Prince

The agenda and the report of the previous meeting, 2003-03-23 in Amsterdam, were accepted as written.

Open Projects

AES-1ID-R, Review of AES-1id-1991 (r2003): Plane-Wave Tubes: Design and Practice
M. Buck produced a draft (posted to the working group document site as "AES-1id-R-PWD-Buck4-031008.doc ") and will produce a revised document for review, 2003-12-15.

AES-5ID-R, Review of AES-5id-1997 (r2003): Frequency and angular resolution for measuring, presenting and predicting loudspeaker polar data
Prince noted that some typographical errors existed in the published document and he will send corrections to the secretariat for inclusion in the next printing. There were no additional comments.

AES2-R, Review of AES2-1984 (r2003): Specification of loudspeaker components used in professional audio and sound reinforcement
Buck will replace J. Woodgate as task group leader. Buck will solicit contributions from experts in each area (for example: Powertest) and assemble with previous elements into a document for submission before 2004-05.

Development Projects

AES-X72, Acoustic Center of Loudspeakers
Prince noted that SC-04-01 has requested cooperation to ensure compatibility between this information document and their own project, AES-X83. B. Olson will forward graphics to Prince for inclusion. Provided these graphics are available, Prince will have a document available for discussion by 2003-12-15.

AES-X129, Loudspeaker Distortion Perception and Measurement
Prince noted that this project will be assigned to task group SC-04-03-D, which has no other projects at present.

In a move to introduce additional expertise relevant to this project, M. Keyhl was introduced and gave a presentation on the development and use of the PEAQ testing method, its successes in the field of codec development and recent moves to apply it to acoustic transmission systems.

T. Welti then showed some results of testing done at Harman that compared audibility metrics against measured distortion level. An experiment used a modified two-way unit where rub and buzz can be induced. Opera (PEAQ) software was used to analyze performance at various levels.

W. Klippel commented that traditional rub and buzz tests look for high harmonics but we need to relate this to what is actually audible. Buck asked about the tolerance of PEAQ tests to ambient noise. Keyhl acknowledged that this issue needed to be considered.

Keyhl also observed that the test setup must have good time alignment, using the calculated propagation delay from the device under test (DUT) to the microphone.

There was a general discussion of test types and source material.

Klippel gave an overview on the work of R. Schmidt who has synthesized loudspeaker distortion and run listening tests. Klippel has posted a description of a similar perceptual test on his website. His data is compared with data from others. He finds that audibility is dependent on the choice of source material, not simply on the measured distortion.

The meeting discussed the prospect of sharing test material, in the form of Wave files, with the members of the working group via the AESSC web site.

Temme volunteered to host on-line meetings for sharing info within a Task Group. Stewart will approach G. Soulodre who specializes in listening tests to discuss the potential for cooperation. M. Kleiner and the Rensselaer Polytechnic Institute may also be able to contribute.

Stewart and Temme will develop a status report and proposal for action on behalf of the task group.

AES-X103, Large Signal Parameters of Low-Frequency Loudspeaker Drivers
Klippel will liaise with ALMA International. Prince is awaiting a document based on the last ALMA meeting.

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 116th Convention in Berlin, 2004-05.