measuring levels

I have read somewhere on the web that Audacity includes a dB level measurement capability but I didn’t find it on the menus (Audacity ver. 2.1.3). Could somebody help me ? Thank you in advance.

The easiest way to find the peak dB level is to select the audio that you want to test, then open the Amplify effect.

By default, the Amplify effect shows how much amplification is required to bring the peak level up to 0 dB.
In this example:

the effect is offering to amplify by +6 dB to bring the peak level up to 0 dB. From that it can be inferred that the current peak level is -6 dB.
Click the “Cancel” button to close the effect without applying.

If you want the “RMS level” (rather than “peak level”), then you can use the “Contrast” tool

dB relative to what? It cannot measure dB SPL (acoustic sound pressure level) because it’s not calibrated to your unknown microphone sensitivity or your unknown preamp gain. Zero dB SPL is approximately the quietest sound that can be heard and SPL levels are positive.

Audacity has recording & playback meters that show dBFS, and there is a little drop-down arrow to the left of the waveform display that allows you to change the scale to dBFS. dBFS is decibels full-scale, where 0dB is the “digital maximum” (1.0 or 100%) so your dB readings are usually negative relative to that reference.

You can get Audacity to indirectly tell you the peak dBFS level of a file, and there are plug-ins for getting the RMS dBFS level.

There are other various electrical dB references, such as dBm or dBV.

Many thanks to steve and DVDoug,
I’ll make some tests and probably comme back to the forum later.
I learn a lot with this forum !

Hi DVDoug and Steve, Hi everybody,
All these issues about dB of various types are a very complex matter. Perhaps it would be easier for me and for you if I write exactly what I would like to do.
I am collaborating with a colleague working on Cubase, preparing the mixing of a work of mine (for 24 instruments) which should be mixed on 8 loudspeakers (3 channels each), which is possible with Cubase for instance. I would like to have each channel’s (variing) volumes tuned after my conception. I have an audio copy of the 24 separate tracks as they are in Cubase now and I tagged for each track (instrument) the places where it plays pianissimo, piano, mezzo forte a.s.o. I named these places my “samples”.
I have volume “samples” for flute playing pianissimo, piano, mezzo forte, forte and fortissimo, for Oboe playing pianissimo, piano, mezzo forte and so on, et caetera.
I’m looking for a way to note the volume of each volume “sample” to give the information to my colleague as “standards” for him in order to have the 24 tracks’ places in Cubase tuned to the same pianissimo, piano, mezzo forte standards a.s.o. I found in the individual tracks I heard to. What is the easiest method to achieve it ?
I hope that my explanation is clear enough. I’m not a specialist in CAM nore in acoustics and English is not my mothertongue !
Perhaps will somebody have an answer ?
I thank you in advance.
Best regards