I can't speak for Boeing...so let's hear it for those that have flown both
If you can't speak for Boeing why you were putting forth a proposition that Boeing's audible signal is perhaps too "soft".
Also it is not a competition who's alarm is louder
. It must be sufficient, which it is. Plus you completely disregarded presence of the visual warning as well.
To date there was no accident report which would suggest that Boeing's AP disconnect alarm is insufficient.