The meeting was convened by chair D. Josephson.
The agenda and the report of the previous meeting, held in New York, 2011-10-22, were approved.
AES42-R Review of AES42-2010: AES Standard for Acoustics - Digital interface for microphones
A brief discussion on the progress of revisions to AES42 was held. J. Breitlow will prepare a report on those manufacturers using the standard, and noted that many were providing only Mode 1 functions.
AES-X085 Detailed Professional Microphone Specifications
There was discussion on the progress of AES-X085. The round-robin test of the example noise source concluded at this meeting with its return to E.B. Brixen. M. Yonge updated the summary document of results, which shows good agreement among the participating labs in their measurements. There was one outlier, and on further analysis it was found that this difference was the result of their use of a 1k ohm load rather than open circuit. Brixen will compile measurements from the lab that built the noise source so any drift can be noted.
Many of the original goals of AES-X085 have been addressed in the two revisions of IEC 60268-4 that have been completed during the period over which the SC has been discussing this project. Much of the discussion in the SC on this topic has been included in the discussion of the IEC MT, many of whose members are also members of the SC. There is still discussion of preferred graphic formats for presentation of performance data.
J. Woodgate suggested that much of this was already defined or recommended in IEC 60265. The CD presently being reviewed by National Committees has been placed on the SC-04-04 website for reference. The chair will prepare a report on remaining issues, to be discussed on the reflector and at the next meeting, with the goal of refining any additional work to be done or reports to be generated within AES-X085.
Woodgate gave a report on the EMC considerations applicable to microphones that were incorporated in IEC 60268-4. Noting the complicated issues around the progress of CISPR 32 and 35 into harmonized standards, the MT incorporated guidance on this topic in the most recent edition of IEC 60268-4.
There was a brief discussion about revisiting the wind and pop susceptibility measurements in IEC 60268-4, with the main issue identified being the inability to specify a uniform turbulent airflow source other than by requiring a given device design.
There were no new project proposals.
There was no new business.
The date of the next meeting will be scheduled in conjunction with the 133rd Convention of the AES in San Francisco, 2012-10.