AES Standards News Blog

AES-X219 Method of measurement for frequency and impulse response of sound systems in auditoria has been initiated and assigned to AESSC Working Group SC-04-08.

The project is scoped to specify a method of measurement for frequency and impulse response of sound systems in auditoria. The output intent is a standard. 

The audience experience of sound reproduced through loudspeakers in an auditorium can vary greatly. In many applications where sound is reproduced in auditoria, a predictable performance is valued. While a number of different electro-acoustic and acoustic parameters contribute to this experience, a standard method of measuring the frequency & impulse response of the sound as presented to the audience by the loudspeaker system(s) will be a necessary part of any more general solution.

http://www.aes.org/standards/meetings/init-projects/aes-x219-init.cfm

http://www.aes.org/standards/development/membership.cfm

AES-X218 Measurement and calibration of sound systems in rooms has been initiated and assigned to AESSC Working Group SC-04-08

New project AES-X216 Calibration Pink-Noise Standard Initiated and assigned to AESSC Working Group SC-04-08

This project will liaise with SMPTE TC-25CSS in their project to "Create a pink-noise Standard, and a reference pink-noise file available in a digital audio file and DCP formats that conform to the description of the pink noise in ST 202:2010 and RP 200-2012 and for which the time domain (mean, standard deviation, skew, kurtosis, etc) and frequency domain (energy per bandwidth, bandwidth, etc) characteristics are defined. Specify the algorithm used to generate the pink-noise file." The project will consider comments as appropriate for communication to SMPTE.

Pink noise generators on the market have measurable differences that can create calibration differences between cinemas. The creation of a stand-alone pink-noise Standard and reference file (with known statistics and characteristics) will eliminate an important variable in the calibration process.

http://www.aes.org/standards/meetings/init-projects/aes-x216-init.cfm

http://www.aes.org/standards/development/membership.cfm

New project AES-X215 Current procedures to calibrate the cinema B-Chain has been initiated and assigned to AESSC Working Group SC-04-08.

This project will liaise with SMPTE TC-25CSS in their project to Codify current procedures as used by skilled theater technicians to calibrate the Cinema B-Chain. The project will consider comments as appropriate for communication to SMPTE.

Current standards for B-chain calibration include ST202 and ISO 2969 which have been used since the mid 1970s, however the effectiveness of this calibration still varies widely. Measurement equipment and technology has evolved since these standards were made. No standardized procedure exists for using modern technology (such as dual DFT-based transfer-function technology) to calibrate cinema theater B-chain systems.

http://www.aes.org/standards/meetings/init-projects/aes-x215-init.cfm

http://www.aes.org/standards/development/membership.cfm

AES66-2012, AES standard for professional audio equipment - Application of connectors - Miniature XLR-type polarity and gender, has been published.

This standard is intended to apply to three- and five-pin circular connectors, commonly and generically known as miniature XLR-type, used for the balanced interconnection of all categories of sound system components for professional audio, commercial, recording, broadcast, and similar applications, regardless of function, type, or level of the signal. It specifies the application and polarity of analog signals for these connectors and is intended to avoid the inversion of absolute polarity among the items in the analog signal chain.

http://www.aes.org/publications/standards/search.cfm?docID=95

AES65-2012, AES standard for interconnections - Connector for surround microphones, has been published.

An increasing number of surround sound microphones are becoming available, however, there has been no common standard for the connectors between microphone and recording device. It is expected that a standard connection will create a basis for smaller and lighter recording devices. 

This standard specifies a connector type and contact assignment for microphones having up to six balanced analog output channels, as used in surround sound applications. It includes specifications for marking and identification for the audio channels. It includes recommendations for cable type and detailed wiring. It is expected that other applications will also use this connection. 

http://www.aes.org/publications/standards/search.cfm?docID=94

 AES2-2012, AES standard for acoustics - Methods of measuring and specifying the performance of loudspeakers for professional applications - Drive units, has been published.

AES-1id-2012, AES Information Document for Acoustics - Plane-Wave Tubes - Design and Practice, has been published

The standard AES2 calls for the use of plane-wave tube measurement of high-frequency horn drivers. Because many variations and results are possible, depending on the details of construction of plane-wave tubes, this document discusses those variations for the purpose of encouraging further experimentation.

This 2012 edition is a revision of AES 1id-1991. Additional uses of a plane-wave tube are listed. Further tests were performed to compare a distant microphone location with a close location to test the hypothesis that non-plane-wave radiation would be more accurately measured. A termination method is described. A modern method of calibration is referenced and summarized.

http://www.aes.org/publications/standards/search.cfm?docID=1

 AES31-2-2012, AES standard on network and file transfer of audio – Audio-file transfer and exchange – File format for transferring digital audio data between systems of different type and manufacture, has been published.

The Broadcast Wave Format is a file format for audio data. It can be used for the seamless exchange of audio material between (i) different broadcast environments and (ii) equipment based on different computer platforms.

As well as the audio data, a BWF file (BWFF) contains the minimum information - or metadata - that is considered necessary for all broadcast applications. The Broadcast Wave Format is based on the Microsoft WAVE audio file format. This specification adds a “Broadcast Audio Extension” chunk to the basic WAVE format.

This revision of AES31-2-2006 incorporates the content of Amendment 1 (2008) that specifies an optional Extended Broadcast Wave Format (BWF-E) file format, designed to be a compatible extension of the Broadcast Wave Format (BWF) for audio file sizes larger than a conventional Wave file. It extends the maximum size capabilities of the RIFF/WAVE format by increasing its address space to 64 bits where necessary. BWF-E is also designed to be mutually compatible with the EBU T3306 "RF64" extended format.

This revision additionally packages a set of machine-readable loudness metadata into the BWF file. This is compatible with EBU v2 broadcast wave files. 

http://www.aes.org/publications/standards/search.cfm?docID=60

 AES55-2012, AES standard for digital audio engineering - Carriage of MPEG Surround in an AES3 bitstream, has been published.

MPEG-D is an ISO/IEC standard describing MPEG Surround that extends mono or stereo audio towards multiple channels. The mono or stereo audio channels represent a downmix of the original multi-channel audio that is generated by the MPEG Surround encoder. In addition the MPEG Surround encoder generates spatial side information (MPEG Surround data). An MPEG Surround decoder is able to combine this information with the downmix to result in a multi-channel audio signal. In this way backward compatibility to mono and stereo systems is achieved.

More recently, MPEG-D has been revised to include MPEG SAOC (Spatial Audio Object Coding) that uses the same method to convey the related side information over PCM.

This standard specifies how MPEG Surround or MPEG SAOC shall be carried within an AES3 bitstream where the downmix channels remain in the linear PCM domain and the MPEG Surround or MPEG SAOC data is embedded into the least-significant bits of the PCM audio data. 

http://www.aes.org/publications/standards/search.cfm?docID=53