How loud?
Sound, or the perception of loudness, is like trying to catch a weasle. (You will understand if you've ever tried). The recording is a good start.
We (where I work) build DC brushless motors. Not cheap. VERY flexible in performance characteristics. SOME have to be VERY quiet. So we measure the sound on some models of every one we make. BUT it takes getting together to agree on a given level - and then using a sound meter to measure it.
Take 10 motors and 10 individuals and you will get wide variation of reports as to which ones are 'noisy' and which ones are OK. The meter doesn't lie.
Cannons, mortars, thundermugs all sound different - length, bore diameter, how loaded and surrounding conditions are all good variables.
Each one, or each type, has it's own 'voice'.
Listen to several and see what you LIKE. Build one for yourself!