Just a few suggestions:
For the measurement of noise, you could consider using a frequency metre and then convert the sound from decibels to phons, because measuring in phons will take into account how loud we perceive the sound, because different frequencies of the same intensity, won't seem as loud as each other. The frequencies could also affect how loud it will sound from inside the case, because higher frequencies don't diffract as much as lower frequency sounds.
Otherwise good review.