I was reading in another PPlace this morning that crew are usually released from their seats when the flaps are fully retracted. Sort of relevant.
As to the OP the easiest souce would probably to lift the audio from a video using Audacity or similar. Or just generate it artificially.
Or you could check out
Singapore_Air's trip reports and no doubt get the sound the the flushing toilet (possibly blocked by 'solid waste') as well as the chimes!