Report of the SC-03-12 Working Group on Forensic Audio of the SC-03 Subcommittee on the Preservation and Restoration of Audio Recording meeting, held in conjunction with the AES 114th Convention in Amsterdam, the Netherlands, 2003-03-22

The meeting was convened by vice chair E B Brixen.

The agenda and the report of the previous meeting in Los Angeles, CA, US, 2002-10-05 were approved as written.

Open projects

AES27-R. Review of AES27-1996 (r2002): AES recommended practice for forensic purposes - Managing recorded audio materials intended for examination.
No actions were taken.

AES43-R. Review of AES43-2000: AES standard for forensic audio - Criteria for the authentication of analog audio tape recordings.
No actions were taken.

Development projects

AES-X10. Guidelines for Forensic Analysis: Study of Requirements for Identification and Enhancement of Recorded Audio Information.
In the report from the last meeting it was stated that a further discussion on this project would be initiated on the reflector. This had not happened yet.

D Begault resumed the discussion from Los Angeles by expressing the opinion that the purpose of AES-X10 was difficult to define. It still was unclear whether it is intended to be a standard, a set of guidelines, an information document, a shopping list, or a methodology. Furthermore it was not clear who this document was to be written for. Begault felt that it would not be practicable to produce a standard.

The standards manager observed that the fundamental purpose of a standard was to specify requirements that could be complied with. This draft could instead be considered for an information document or a report.

Several people voiced the opinion that the equipment should not be included in the main document as this aspect may change over time. However the assessment of recording equipment involved in forensic work was also felt to be important. Being audio engineers the members of an AES workgroup should be able to decide on equipment appropriate for the work. Equipment used would normally be available to every engineer.

It was decided that Begault should initiate a discussion on the reflector in order to make a better basis for a decision on this document. All members of the SC-03-12 are invited to forward their comments.

The standards manager informed the meeting that a new project initiation form soon will be available. This will help to clarify the aim of future projects from the very beginning.

AES-X135. Forensic audio - Recordist Audio Evidence Collection (FARAEC)
The version of the AES-X135 presented to the workgroup was the 2002-12-02 version as found on the SC-03-12 document site. (This version contains the standards manager's comments).

The discussion progressed very much like the AES-X10 discussion: it was generally felt that this project is not suitable for a standard, but would be appropriate for an information document.

The meeting felt that the documents in general should contain as few acronyms as possible. Hence the "FAR" should be written as the "forensic audio recordist" or just the "recordist".

Some expressions need further explanation. The meaning of "privacy" has to be considered in the knowledge that the legal sense of this word may be interpreted very differently in different countries. Because the AES is an international organisation, consideration should extend beyond US law.

Even though the good intentions behind the specification of the Compact Cassette as a safe format for forensic recording were well known, the meeting felt that recording equipment should not be specified in this document. Different recording equipment is used in different countries. Even digital equipment is now being used for legal recordings. If equipment eventually is to be evaluated for forensic recordings, the results should be presented in another document or in an appendix.

However the choice of the microphone type/quality and its placement is evident and should be stated more clearly.

In conclusion, P Merrill was encouraged to provide a revised draft PWD.

New projects

Brixen mentioned the low bit rate algorithms that are used in connection with dictation machines, surveillance recorders etc. A better understanding is needed for accepting or rejecting these recordings when used for speech comparison. On the reflector it had been mentioned that R Alexanderson (Voice ID Inc.) had been doing some comparisons. Begault invited the group to collect results of different spectrographic/aural voice comparisons carried out by the group members. This could later end up as a group document.

New business

There was no new business.

The next meeting will be held in conjunction with the AES 115th Convention in NY, US.