Know the amplitude (volume) of a file.

Audacity 3 Help Forum Windows
1

Hello everyone!

I would like to know if there is any way to know or measure the exact amplitude (volume) of a file? Reason why I intend to leave all my video-lessons with the same volume.

Thank you very much!

2
  1. Select the audio that you want to measure (it could be the entire track, or just part of a track)
  2. Open the “Amplify” effect.
  3. Observe the default “Amplification (dB)” setting.
    By default, the Amplify effect offers to amplify up to 0 dB, so the “Amplification (dB)” setting shows the number of dB required to make the selection up to 0 dB. Put another way, it shows the number of dB below full track height.
  4. Click the “Cancel” button to close the Amplify effect.

Example: If the peak amplitude of the selected audio is -20 dB, then the Amplify effect will offer to amplify by +20 dB. Thus, if the default “Amplification (dB)” says “20”, then we know that the peak amplitude of the selection is -20 dB.

1 Like
3

Hi Steve!

First I ask you to please consider my faults regarding the duplicity of the topic, it was my distraction.

Regarding your example, get this straight: If the peak amplitude of the selected audio is at -20dB, the Amplify effect will offer and present +20dB amplification. In this example, can we conclude that the audio (-20) is too low and needs to be applied (+20) to be normalized to the 0 (zero) standard?

Not to open another topic, on one occasion I met a puglin that makes the audio uniform (single volume) mainly the voice. Could you let me know what this puglin would be so I can download it?

Thank you very much friend!

4

Do you mean that it made loud voices quieter and quiet voices louder?
If so, that may have been the Nyquist plug-in: “Level Speech” which you can get here: Missing features - Audacity Support
Instructions for installing Nyquist plug-ins: https://manual.audacityteam.org/man/installing_effect_generator_and_analyzer_plug_ins_on_windows.html#nyquist_install

5

Hi Steve!

I was hoping you would be able to give me some insight on a problem I am running into. When I find the amplitude of a set audio using the method you described I get -20.616 dB. When I go to analyze → plot spectrum I get -28.9 dB for the peak frequency of the audio. Do you know why these values are 1) differing from one another 2) the peak frequency is registering a lower amplitude? Which of these readings is more reliable? Any guidance would be greatly appreciated!

6

When you run Amplify, that’s the highest actual sample-value in the file (converted from a floating-point number to dBFS).

The spectrum is dividing-up the audio into frequency bands and the level is usually lower than when everything is combined together in the waveform view (or in the actual raw time-domain audio data).

If you have a single pure tone, the level should be about the same in both.

Note that peaks also don’t correlate with perceived loudness. RMS is a kind of average and it’s better measure of loudness than peak. (Analyze → Measure RMS).

LUFS loudness is even better, and although Audacity has Loudness Normalization built-in to set the loudness, it can’t just measure it. There are 3rd-party plug-ins that might work in Audacity or there is an online loudness tool.