Increasingly, digital music is excessively compressed, to ensure that the selection is not perceived by the listener as being too soft in comparison with other sources, a trend known as the loudness war.
The result was a wide disparity in audio levels when changing between digital broadcast channels through over-the-air and cable distribution.
[3] This technique utilizes a weighting curve with a smaller amount of low frequency de-emphasis, and introduces a peaking emphasis to compensate for the boost in loudness perception caused by the shape of the human head.
This new step, contributed by the EBU PLOUD committee, stipulates additional processing to allow selection of the audio segment to be measured.
In November 2009 the ATSC released recommended practice A/85: "Techniques for Establishing and Maintaining Audio Loudness for Digital Television".
[4] This document was developed to improve understanding of program loudness, the dialnorm parameter, appropriate management techniques and options for system implementation.