TC Electronic’s CTO for Broadcast & Production, Thomas Lund, took a number of mobile devices, including Apple’s iPhone and iPad, to the test bench at the ‘TC Lab.'
Based on the test results, it is determined that -16 LUFS/LKFS is a suitable target level when making the transition from HD audio to mobile platforms. It is not recommended to push level up further, but rather to integrate a process of three simple steps to simulcast HD audio to mobile that doesn't wash out the distinction between foreground and background sound.
It is also not recommended to let audio sit as low as on regular TV, because some programs will not be able to play loudly enough for a listener on the move. This has happened to the author of the paper a number of times, which led him to carry out the experiment and come up with a practical guide to how this problem can be addressed.
Lund also elaborates on perception, clarity and speech intelligibility before concluding that the 400ms sliding window of Momentary Loudness in EBU and ITU standards is a well-indicated choice.
The paper was originally written for the Broadcast Engineering Conference at the 2013 NAB Show, at which the research results were presented for the first time. The full paper and test results can be downloaded as a pdf file here.
