How to record audio files
All voice audio (dialogs, words, etc), should be MONO, 44.1KHz files and should be well trimmed at beginning (at zero crossing!)
Level shoudl be normalized with a peak reference at -6db
In the Unity project they are saved in MP3 format, with middle quality VBR (Variable Bit Rate).
To easy the voice audio normalization we have a macro script for Audacity: you can find it here: Antura Normalize Vocabulary - Audacity macro.txt
because we have lots of voice audio files and don't want to waste app space, and voice recordings just need mono and medium compression.
Audacity is a perfect free multiplatform tool to edit audio files.
on macOS we use the free utility xAct to batch convert audio files.