Report of the SC-04-04 Working Group on Microphone Measurement and Characterization of the SC-04 Subcommittee on Acoustics meeting, held in conjunction with the AES 116th Convention in Berlin, 2004-05-09.
The meeting was convened by chair D. Josephson.
The agenda and the report of the previous meeting, held on 2003-10-12 in New York, were approved.
Open Projects
AES-42R, Review of AES-42-2001: AES Standards for Acoustics - Digital Interface for Microphones.
The meeting of Task Group SC-04-04-D which had occurred on 2004-05-08 was discussed. Task Group leader C. Langen presented its report which has been distributed on the SC-04-04-D reflector as well. Langen reported that all open editorial corrections had been made, and several items discussed and resolved which had been left open as of the previous meeting. The issues remaining, regarding parameters to be passed to a compressor/limiter integrated into the digital microphone or similar device, were resolved and the next revision draft of the standard will be ready at the next meeting.
Development Projects
AES-X62: Psychoacoustics of Microphone Characteristics and AES-X63
No activity to report. Rather than retiring these projects, the chair recommended leaving them suspended in case the work on AES-X85 requires additional input in these areas.
AES-X93: Recommendations for Revisions of IEC 61938 Clause 7.
There was no discussion on this project.
AES-X85: Detailed Professional Microphone Specifications
Work is proceeding on the round-robin test of microphones among manufacturers as defined at the 2003-10 meeting. The practical details are being handled by task group SC-04-04-E but the task group meeting was held concurrently with this part of the working group meeting. It was hoped that the results of the first tests would be presented at this meeting, but it was not possible due to the absence of the technical participants from the relevant company. Other members presented some test data for their own microphones in formats addressing the parameters defined at the 2003-10 meeting. The majority of the meeting was spent with technical discussions of test methods. Participating members will forward their interim test results to the task group reflector and its document site.
New Projects
No new projects were proposed.
New Business
J. Brown briefed the WG on progress in the matter of evaluating microphone performance in the presence of strong RF fields. At present microphones are generally treated as passive devices for EMI/EMC issues but it may be necessary to review this position. It is partly an issue of received EMI conducted through the cable to the input of the mixer or preamp, but microphones containing active circuits present a unique EMC problem of their own, and it has been demonstrated in several recent papers that microphones vary greatly in their ability to cope with external RF fields.
The next meeting will be scheduled in conjunction with the AES 117th Convention in San Francisco, CA., US., 2004-10
