AES Standards News Blog

AES75-2022, "AES  standard for acoustics – Measuring loudspeaker maximum linear sound levels using noise" has been published on 2022-03-04.

This standard details a procedure for measuring maximum linear sound levels of a loudspeaker system or driver using a test signal called M-Noise. In order to measure maximum linear sound levels meaningfully and repeatably, a signal is required whose RMS and peak levels as functions of frequency have been shown to be representative of program material. Various existing standards define noise-based test signals which, like M-Noise, have incorporated the knowledge that typical program material has a diminishing RMS level with increasing frequency, but M-Noise uniquely also features a relatively constant peak level as a function of frequency, so that the crest factor (peak level – RMS level) increases with frequency, which an analysis on a large variety of music and other content has revealed is an important additional characteristic of typical program material. The specified procedure determines a loudspeaker’s maximum linear sound levels by incrementally increasing the Playback Level of M-Noise until a stop condition is met: either an unacceptable change in the transfer function’s magnitude or an unacceptable change in the coherence of the transfer function.

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The Call for Comment on DRAFT AES76-xxxx, "AES standard for audio forensics - Speech Collection Guidelines for Speaker Recognition: Interviewing at a Temporary Location" was published 2022-02-03.

This document specifies recommended practices for recording audio intended for use in forensic speaker recognition analyses, focusing on doing so at a temporary, non-laboratory location by possibly a nonprofessional in the forensic sciences. It includes recommendations for the physical preparation of the location, selection of appropriate recording hardware and audio formats, and possible methods for interviewers to elicit the desired type and amount of speech from subjects. It does not cover the methods used to analyze the resulting recordings and does not deal with details related to the handling, transmission, storage, or preservation of the collected data but will include a checklist to aid in the process.

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The slides from Marisa Dérys recent webinar on the work of the AES Standards Working Group on Forensic Audio, SC-03-12, are available for download.  These are copyrighted and are for individual educational use only. Reproduction or any other use requires written permission of the AES Standards Manager.

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Three profiles for Precision Time Protocol (PTP) might potentially be used in the professional media environment: the Peer-to-Peer Default PTP Profile of IEEE Std 1588-2008, the Media Profile of AES67 and the SMPTE Profile of SMPTE ST 2059-2.  This report compares the profiles and identifies features and parameter ranges that should enable interoperability among equipment conforming to the different profiles.

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The Call for Comment on DRAFT AES75-xxxx, "AES standard for acoustics – Measuring loudspeaker maximum linear sound levels using noise" was published 2022-01-10

This standard details a procedure for measuring maximum linear sound levels of a loudspeaker system or driver using a test signal called M Noise. In order to measure maximum linear sound levels meaningfully and repeatably, a signal is required whose RMS and peak levels as functions of frequency have been shown to be representative of program material. Various existing standards define noise based test signals which, like M Noise, have incorporated the knowledge that typical program material has a diminishing RMS level with increasing frequency, but M Noise uniquely also features a relatively constant peak level as a function of frequency, so that the crest factor (peak level – RMS level) increases with frequency, which an analysis on a large variety of music and other content has revealed is an important additional characteristic of typical program material. The specified procedure determines a loudspeaker’s maximum linear sound levels by incrementally increasing the Playback Level of M Noise until a stop condition is met: either an unacceptable change in the transfer function’s magnitude or an unacceptable change in the coherence of the transfer function.

More Information and to download a copy

The slides from Jeff Berrymans recent webinar on AES70 are available for download.  These are copyrighted and are for individual educational use only. Reproduction or any other use requires written permission of the AES Standards Manager.

Download a copy here

Some reports of the Fall AES Standards Working Group meetings are now online.

SC-02-02 on Digital Audio Interfaces
SC-04-03 on Loudspeaker Modeling and Measurement
SC-04-04 on Microphone measurement and characterization
SC-04-09 on Assessment of acoustic annoyance

Additional reports will be posted as they become available.

View the reports here

IEC-60268-16 rev. 5 describes test signals in Annexes A and C that are intended to be used to verify STIPA implementations. If you are implementing STIPA in software or firmware, we recommend that you closely study the standard (including Annexes A and C) and take guidance on verification requirements that are given there. A summary of the test signals, and how these are to be used, are given in the IEC-60268-16 Test Signal description that can be downloaded from the AES Standards web site.

Download the signals here

The remaining reports of the May AES Standards Working Group meetings are now online.  

SC-02-08 on Audio-file transfer and exchange
SC-02-12 on Audio-applications-of-networks
SC-05-05 on Grounding and EMC Practices

View the reports here

AES67 has made low-latency, synchronized, and uncompressed audio delivery commonplace on local area networks (LANs). As the need to provide two-way interaction between multiple sites rises, there is a desire to extend AES67 solutions into Wide Area Networks (WAN) and datacenters. This report examines the requirements and challenges when AES67 is extended beyond LAN environments. After describing the operational environments and associated constraints in detail, this report will address timing, transport and data reliability in the context of WAN and cloud. The report shows that none of the discussed environments is associated with a specific single problem, but instead, there are a number of smaller technical factors that interact and need to be addressed. While this study indicates that bit-precise transmission, synchronization and timing alignment is reasonably achievable, very low latencies, use of multicast, and 100% reliable reception remain challenging or impossible. Field experience annexes included in this report correlate well with the theoretical expectations based on this study. Robustness of AES67 is confirmed by its success on WAN production facilities and long-distance deployments. It brings generally better audio quality, latency performance and routing flexibility, compared to point-to-point transport based on lossy compression.

This document was developed in the SC-02-12-M task group on AES67 development under the leadership of Nicolas Sturmel.

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