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 Warsaw 2015-05-08
The meeting was convened by chair D. Josephson.
The draft agenda and the meeting report from Los Angeles, 2014-10-10, were approved as presented.
Development projects
AES42-R Review of AES42-2010: AES Standard for Acoustics - Digital interface for microphones
This standard requires review before the end of 2015. Unless some proposal for revision is received, it should be reaffirmed.
Development projects
AES-X085 Detailed Professional Microphone Specifications
The main discussion centered on work proceeding under AES-X085, various aspects of detailed professional microphone specifications.
Juergen Breitlow had asked members to upload .wav files of noise sources, noisy microphones etc. to validate the implementation of quasi-peak (ITU-R BS.468-4) measurement code provided by H. Riekehoff-Boehmer from Schoeps by comparison with older equipment thought to be compliant with ITU-R qpk, but no one has done this yet. There are separate folders on the SC-04-04 site for the quasi-peak algorithm project and the improved wind/pop noise measurement project.
The sample code was written in Matlab. Brietlow is porting it to Octave which offers similar capabilities but free and open source. He expects to present the Octave code by the next meeting.
Work continues also on the improved measurement of wind and pop sensitivity. German DKE committee will be meeting in two weeks’ time to discuss this further, Breitlow will report on progress. IEC 60268-4 contains methods in the body of the standard which are thought to be inadequate, and alternative methods developed by ITU which are better. Breitlow will discuss with S. Goossens who has been driving this effort at IRT so that their recommendations can be incorporated directly. As discussed in previous meetings many manufacturers are using 5 to 7 m/sec wind which is considered adequate for susceptibility of bare microphones but not for advanced windscreens (60268-4 recommends 10 m/s.) Still planning a round-robin test once more companies are on board with the new test method, sending one or two microphones around for comparison. DPA is supporting this with samples, C. Woolf at Rycote also supporting the effort.
Liaisons:
There were no liaison reports. There was some discussion of including the revised wind/pop measurement recommendations in the next revision of IEC 60268-4.
New projects
Network control of microphones: A new project was discussed to develop a uniform parameter set (values, ranges, naming conventions) for digital microphone remote control. This would be applicable both to AES-X210/Open Control Alliance and other efforts such as Amber Plus. Breitlow will report on existing discussions between manufacturers implementing remote control microphones. The target of this work is an information document to be made available to anyone developing network control.
An additional project was discussed to document the existing analog microphone remote pattern control protocol developed and patented by Neumann (its patent has since expired.) Josephson will initiate a project to do this.
New business
There was no new business.
The next meeting will be scheduled in conjunction with the AES 139th Convention in New York, NY., US., 29 October to 1 November, 2015.
