APU Software

Loudness Meter

Free loudness metering and audio file analysis

Free

APU Loudness Meter is a free plug-in for measuring loudness and dynamics. Follow the audio in real time with history and histogram views, or analyze a file to see its overall statistics.

Loudness types: LUFS (Momentary, Short-term, Integrated), RMS, Peak, and True Peak.
Multi-channel: Supports stereo, surround, and Dolby Atmos® formats.
Channel modes: Measure channels separately or together.
Visualizations: Live histogram and time-history views with configurable history lengths.
Output metrics: Monitor source, history, global, PSR, PLR, and Crest measurements.
Statistics: View min, peak, average, LRA, and Integrated LUFS.

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System requirements: macOS 10.14 (x64, ARM), Windows 10 (x86, x64), OpenGL 3.2.
Supported software formats: Standalone application, VST, AU, AAX (Pro Tools 11+).

Loudness Types

Choose a measurement type based on what you want to inspect:

Momentary

Momentary measures loudness over a 400 ms window with K-weighting and channel weighting. You can adjust the window for a faster or slower response; 400 ms is the standard Momentary setting.

Short-Term

Short-Term measures loudness over a 3-second window, making longer changes in level easier to see. It uses the same K-weighting and channel weighting as Momentary.

Integrated

Integrated measures loudness over the measurement run, using K-weighting, channel weighting, and relative and absolute gating.

RMS

RMS measures signal level over an adjustable window, set to 150 ms by default. It does not apply K-weighting or channel weighting.

True Peak

True Peak estimates peaks between samples as well as sample peaks. Measurements use the configured block interval.

Peak

Peak measures sample peaks over the configured block interval. It does not estimate peaks between samples.

Credits

Developed by APU Software, LLC with the following libraries:

JUCE (cross-platform audio and user interface framework)
Boost (header-only algorithms)
libebur128 (loudness measurements)
melatonin_blur (blur effects)

Demo video song credits:

Annasara - A Lifetime Rolls By, licensed via Audiio.