What is the ideal decibel? Do we need to adjust volume of datasets?

Hi, I’m training speech recognition model for Japanese with my own datasets.

Parts of my datasets are very low audio.
Should I increase volume of such audios before training?
If I normalize audio, is it better?

What average decibel is ideal?
I mean I may have to decrease volume when too loud.

Thanks in advance.

When used in production do you expect the volume of the audio to change significantly or do you expect all the audio to be approximately of the same volume?

Volume can be approximately the same even though i’m not sure i can release it as a real product…

Thanks for your advice.