Search for the "Audio Engineering Society" website. They list some room ratios for best room acoustics.
When I was building my house, I saw one formula that I liked:
1H: 1.57W: 1.87L
It seems to start with the HEIGHT of the ceiling.
I wanted a ceiling height of 14FT (since I thought it was a good number
) ---- so my room room dimensions came out to be:
14'H x 22'W x 26'L.