Question

what makes good architectural acoustics?

Answer 1

My ex works as an Acoustical Consultant and there is no short answer, as it depends on what you want a space to do, acoustically speaking.

This is something you should research on the web.

Answer 2

This can vary depending on the final requirements, are you designing a concert hall , hospital or hotel. Do you want noise reduction or enhancement?
How many people will be in the spaces you design at a single moment and what materials will be used in the construction?
Do you have a more specific question?