Report of the Meeting of the SC-04-04 Working Group on Microphone Measurement and Characterization of the SC-04 Subcommittee on Acoustics, held in New York, NY., US., 2013-10-19
The meeting was convened by chair D. Josephson.
Noted that there had been no meeting at the Rome AES convention, 2013-05.
AES-X085 Detailed Professional Microphone Specifications
Discussion on focused on continuing improvement of noise metrics, specifically a more precise definition of the time domain response required to comply with ITU-R BS.468-4. The round-robin tests and members' reports indicate significant differences among the various digital implementations of this measurement method. The language of the ITU standard appears to be anticipate the use of an analog meter movement for the display mechanism, while most users employ a device having a digital readout, requiring algorithmic simulation of meter ballistics. The frequency domain weighting curve is precisely documented in the standard, with tolerance bands, but there is no such precision for the quasi-peak detector.
Subsequent to the meeting, John Woodgate reported to the chair that there was a possibility for liaison with ITU via the IEC for incorporation of our recommendations on BS.468-4.
Steve Temme reported that he had made available a sample audio file of Gaussian noise for testing of various meters. There was discussion that other users would submit files with other noise signals that might be used in comparing detectors.
Work on providing guidance to IEC TC100 is also being carried out under AES-X085. Juergen Breitlow reported progress on improved wind and pop sensitivity metrics and will give a report at the next meeting, in Berlin 2014-04.
David Bock discussed providing guidance to consumers of microphone data (also a part of AES-X085) with regard to deciphering the "scrambled eggs" of microphone specifications. This follows a very well attended workshop convened by Eddy Brixen at this convention on this topic. Bock will work on a draft outline of a document which might become an information document or a report from the Technical Council with input from SC-04-04.
AES-X085 status should be revised to indicate a goal target of 2014-04 for a status report.
New Projects
No additional liaison matters were discussed.
New Projects
Mike Williams reported some problems with the connector that had been adopted, at SC-04-04's suggestion, in the AES65 standard developed by SC-05-02. Users are reporting difficulty terminating individual cable pair shields in the standard connector, and more channels than the initial 6 are needed. Williams and Eddy Brixen will prepare a report on a suggested extension of AES65 to incorporate a larger connector and preferred color coding for the additional channels, to be issued as a recommendation to SC-05-02 for revision of AES65.
New Business
No new business was proposed.
Next meeting wil be schedled in conjunction wit the AES 136th Convention, Berlin, 2014-04.
