The Loudness Meters provide data about an audio file's momentary loudness, short-term loudness, integrated (overall) loudness, and loudness range. You can use these values when mastering for broadcast to ensure compliance with loudness standards (such as the CALM Act).
If the Loudness Meters are not visible, you can select the Show or hide the bottom pane button or choose View > Loudness Meters. For more information, see "Arranging editing views."
The meters display real-time values for each of the following measurements:
The M meter represents the momentary loudness — in loudness units (LU) — across all audio channels based on 400-millisecond integration windows. The Momentary box displays a numeric representation of the momentary loudness.
The S meter represents the short-term loudness — in loudness units — across all audio channels based on 3-second integration windows. The Short box displays a numeric representation of the short-term loudness.
The I meter represents the integrated loudness — in loudness units — across all audio channels over the duration of the program. The Integrated box displays a numeric representation of the integrated loudness and includes an over-target indicator.
The LRA meter represents the loudness range — in loudness units — of the momentary and short-term levels. The Loudness Range measurement provides a standardized method of determining the dynamic range of the signal.
The True
peaks meter represents the peak levels in dB FS. True peaks are
calculated using a higher sample rate than peaks in the
Meters tool for increased accuracy. For more information, see "Monitoring peak levels."
The clipping indicator on the True Peaks
meter shows you whether the target loudness has been exceeded. The
indicator is reset when you restart playback, or you can click the indicator to reset it.
The statistics at the top of the tool can display the maximum or last-calculated (current) values. Choose Current, Max, or Reset from the menu at the end of the statistics bar to change the display.
Loudness is recalculated whenever you start, stop, seek, or change playback direction. If you want to force a recalculation, choose Reset from the menu at the end of the statistics bar.
Select the Enable surround
processing on 5.1 mediacheck box on the Advanced tab in the Loudness Meters tool if you want to treat audio with six channels
as surround audio when measuring loudness (a gain of ~1.5 dB is applied
to the left and right surround channels). When the check box is cleared,
all channels contribute equally to the loudness measurement.
When Loop Playback is selected, the selection must be greater than 2.5 milliseconds to use the Loudness Meters.
To change the mode of the meters, click the General tab in the Loudness Meters tool, and then choose EBU R 128 or ATSC A 85 from the Mode drop-down list.
When using EBU R 128, the target value of the Integrated meter is -23 LUFS, and the maximum True peak value is -1.0 dB FS. Use this mode when you're mastering to European Broadcasting Union (EBU) standards.
When using ATSC A 85, the target value of the Integrated meter is -24 LUFS, and the maximum True peak value is -2.0 dB FS. Use this mode when you're mastering to North American Advanced Television Systems Committee (ATSC) standards.
The over-target indicators will be triggered if the target values for Integrated and True Peaks meters are exceeded.
To change the scale of the meter, click the General tab in the Loudness Meters tool, and then choose EBU +9 or EBU +18 from the Scale range drop-down list.
When using EBU +9, the meters are displayed with a range of -18 to +9 LU.
When using EBU +18, the meters are displayed with a range of -36 to +18 LU.
Choosing a wide range allows you to see low-level signals at the expense of precision display at high levels.
Select Absolute scale (-23 LUFS) if you want to display loudness values as Loudness Units Full Scale (LUFS). When Absolute scale (-23 LUFS) is not selected, all values are expressed as Loudness Units (LU) relative to the selected mode (EBU R 128 Mode or ATSC A 85 Mode).
To toggle the True Peaks meters in the Loudness Meters, select the True peak meter check box on the General tab in the Loudness Meters.
Please note that true peaks are calculated using a higher sample rate than peaks in the Channel Meters for increased accuracy. For more information, see "Monitoring peak levels."
Peak levels may be miscalculated if audio signals are asymmetrical or if a DC offset is present. To enable filtering, select the Advanced tab in the Loudness Meters and then select the True peak blocking filter check box. When True peak blocking filter is selected, peaks are calculated as the maximum of the filtered and unfiltered signals.
The True Peaks meters display levels in dB FS. To change the resolution of the meters, choose a setting from the True peak meter drop-down list on the General tab in the Loudness Meters.
Choosing a wide range allows you to see low-level signals at the expense of precision display at high levels.