Anyone have suggestions for sound deadening interior finishes?

[Jeremy]

Does the vinyl really absorb sound? 

You'll notice that Eric specifically said 'mass loaded vinyl'; this is something else I'd not heard of before (I've learnt a lot from this thread!), but, courtesy of Mr Google, there's now no question in my mind that mass loaded vinyl is the 'lead substitute' material in my layered foam soundproofing that I mentioned earlier.


Jeremy

[belfert]

Does the vinyl really absorb sound? 

You'll notice that Eric specifically said 'mass loaded vinyl'; this is something else I'd not heard of before (I've learnt a lot from this thread!), but, courtesy of Mr Google, there's now no question in my mind that mass loaded vinyl is the 'lead substitute' material in my layered foam soundproofing that I mentioned earlier.

He said to use mass loaded vinyl for the floor.  For the walls he said to use upholstery foam with cloth or vinyl over it.  I'm fairly certain he meant upholstery vinyl for the walls.

My question is would upholstery vinyl really help absorb sound?

[Jeremy]

You're right, he did - my bad.

Regarding the foam-backed upholstery vinyl - I would think that most of the (fairly limited) sound-proofing benefit of this would come from the foam component rather than the thin layer of vinyl on top of it. Foam is effective against higher-frequency sounds as has been explained, although the foam you get behind upholstery vinyl is only 3 or 4mm thick, so is obviously not going to do a whole lot even with those sounds.

You mentioned right at the start that your bus interior has plain plywood walls - is there anything behind that plywood? If not, you'll obviously get a far greater benefit in doing something with the space there than you will get from the final decorative interior finish.

Jeremy

[belfert]

The plywood is screwed directly to the metal framing.  There is either spray foam or pink foam insulation in the cavities between the metal framing members.