Report of the SC-04-04 Working Group on Microphone Measurement and Characterization of the SC-04 Subcommittee on Acoustics meeting, held in New York, 2005-10-08.

The meeting was convened by chair D. Josephson.

The agenda and the report of the previous meeting, held in Barcelona, 2005-05-29, were approved as written.

Open Projects

AES-42R, Review of AES-42-2001: AES Standards for Acoustics - Digital Interface for Microphones.
The draft for revision of AES42-R was felt to be complete. Unless there is some objection, it is proposed to move it to PCFC.

Development Projects

AES-X85: Detailed Professional Microphone Specifications
Work continues on the project AES-X85 within task group SC-04-04E. Because of the general interest in this work, task group leader Josephson has been holding meetings concurrently with the working group meetings, which was again the case with this meeting.

The main discussion was on the topic of self-noise measurement, which was the area of the round-robin test showing the greatest discrepancy among measuring labs. It was noted that the IEC standard contains an error, referring to a combination of weighting curve and detector type that is not practical. It was felt that this was probably due to a compilation error of the current standard. In order to help resolve the differences between labs in measuring microphone noise output, E. Brixen from DPA offered to produce a standard noise test source which could be evaluated by each of the labs participating in AES-X85 to see whether we can reach consensus on a testing method.

AES-X093: Recommendations for Revisions of IEC 61938 Clause 7
At the request of member H. Jahne, who was not present, the group discussed difficulties with phantom power. We are planning to once again urge IEC to revise IEC 61938 to keep up with advances in circuit topology. Jahne was particularly concerned about the imbalance in phantom power current drawn by microphones, which is permitted by the current standard but not by its predecessor DIN 45 596. The WG will continue to research modifications that can be recommended to the IEC standard.

New projects

No new projects were requested.

New business

There was no new business.

The next meeting will be scheduled in conjunction with the AES 120th Convention in Paris, France, 2006-05