Loudness Measurement

Loudness Measurement

The following measurements are performed:

• Integrated Loudness

  Average loudness that is measured over the whole program in LUFS (Loudness Unit, referenced to Full Scale).

  According to the loudness recommendation R 128, audio should be normalized at -23 LUFS (±1 LU).

• Short-Term Loudness

  Loudness that is measured every second on an audio block of 3 seconds. This gives information about the loudest audio passages.

• Momentary Loudness

  Maximum value of all momentary loudness values that are measured every 100 ms in an audio range of 400 ms.

Loudness Range

The loudness range measures the dynamic range over the whole program in LU (Loudness Units). It reports the ratio between the loudest and the quietest non-silent sections. The audio is divided into small blocks. There is one audio block every second, and each block lasts 3 seconds so that the analyzed blocks overlap.

The top 10 % of the quiet blocks and the top 5 % of the loud blocks are excluded from the final analysis. The calculated loudness range is the ratio between the loudest and quietest remaining audio blocks. This measurement helps you to decide how much compression or expansion must be applied to the audio.

True Peak

When a digital signal is converted to an analog signal, EBU R 128 recommends that you rather measure an estimation of the real peaks instead of relying on digital peaks. This avoids clipping and distortion.

Naming and Units

EBU R 128 proposes the following naming and units conventions:

• A relative measurement, such as a value that is relative to a reference level, LU as Loudness Unit (1 LU is 1 dB).

• An absolute measurement, LUFS as loudness unit referenced to full scale. 1 LUFS can be understood as 1 dB in the AES17 scaling.

Scales

The loudness meter offers two different scales:

• The EBU +9 scale has a range from -18.0 LU to +9.0 LU (-41.0 LUFS to -14.0 LUFS).

• The EBU +18 scale has a range from -36.0 LU to +18 LU (-59.0 LUFS to -5.0 LUFS).