FFmpeg notes (including FFmpeg install): https://www.rickmakes.com/ffmpeg-notes/
FFmpeg playlist: https://www.youtube.com/playlist?list=PLErU2HjQZ_ZOPDZ71Khzt5PX4X4j6flkg
FFmpeg mapping inputs to outputs: https://trac.ffmpeg.org/wiki/Map
View Video Settings
ffprobe noisy_audio.mov
Extract Audio Track as WAV Format
ffmpeg -i noisy_audio.mov -vn noisy_audio.wav
Modify audio file in software like Audacity. In my case, I added a reverb to the whole file.
Create a New Movie with Original Video and Newly Edited Audio
ffmpeg -i noisy_audio.mov -i noisy_audio_reverb.wav -vcodec copy -map 0:v:0 -map 1:a:0 -acodec aac noisy_audio_reverb.mp4