The LRA instrument provides a graphical representation of the Loudness Range (LRA) descriptor. LRA is a statistical method used to measure the variation of loudness across an entire program, where lower LRA values represent lower program dynamics. In this way, the LRA measurement can show whether a program has a continuously constant loudness (low LRA values) or a high variation between low and high level components (high LRA values).
There are no common target LRA values defined in the loudness standards, but some broadcasters or streaming services around the world define maximum LRA values in their delivery standards.
In general, the three distinct areas Comfort Zone (average LRA values), High Range (high LRA values) and Low Range (low LRA values) are used that can help to classify a program with regard to its LRA measurement and mark it with a distinct color.
The MagicLRA mode available in the LRA instrument uses a scale with a fixed centered zero position (corresponding to the target level) where the LRA bar spreads symmetrically from the 0 position and its length is a measure of the absolute LRA value.
The MagicLRA + I mode is a combination of LRA and Integrated (I) loudness measurements. The LRA bar has a moving, relative zero position that is anchored to the Integrated value measured. The MagicLRA + I + Num mode provides an additional display of the numerical LRA value on the zero position.