The 132nd AES (Audio Engineering Society) Convention concluded in Budapest yesterday. The EBU's Loudness Recommendation R 128 was on the agenda in two different contexts, in both cases representing further endorsement. R 128 allows broadcasters to measure and normalize audio using loudness meters instead of peak meters only, which improves the listening experience for the user.
R 128 for online content
While R 128 was developed primarily with broadcasting in mind, testing done in the context of the NoTube project (see right) has confirmed that it can be applied with similar success to online content. The tests were done by the IRT, the primary research institute of EBU Members in Germany, Austria and Switzerland. They were designed to investigate the interdependence between loudness harmonization, loudness range characteristics and listening conditions, taking account of the varying conditions under which online content is consumed. In the context of NoTube, the user’s listening environment can typically be characterized as a computer-based listening environment with built-in laptop speakers or small external PC speakers.
The final test results, as announced in Budapest, again verify the sufficiently accurate approximation of human loudness perception by the algorithm defined in R 128 (and ITU-R BS.1770-2) not only for broadcast audio signal, but also for the audio part of video clips presented over the internet. Where the individual listening level was adjusted on a speech-based test sequence to a target loudness of -23 LUFS, the level recommended by R 128, a significantly clear preference for the same loudness value was observed for all of the other test items.
Loudness Metadata in AES 31
Also in Budapest,the AES Standards Committee Working Group on Audio-File Transfer and Exchange decided at its meeting to update its AES 31 standard with the loudness metadata that the EBU added to the EBU BWF format earlier this year. This will allow users to signal five key loudness parameters describing the content in the file, as described in R 128:
• The Integrated Loudness value of the file
• The Loudness Range (LRA)
• The maximum true peak level
• The maximum momentary loudness level
• The maximum short term loudness level
More information on these parameters can be found here: tech.ebu.ch/loudness