Some other practical considerations which should be taken into account are:
who and what needs to be in the enclosure during operation of the noisy equipment
(personnel should be excluded if possible);
number and location of doors and windows (minimum possible);
method of door closure (manual, automatic) and type of latch to ensure a tight seal around
the door perimeter;
automatic machine stop when doors are not closed properly;
ease of cleaning inside the enclosure;
ease of maintenance of enclosure and enclosed equipment;
resistance of sound absorbing material to oil, dust, water or other chemicals; and
attractiveness of finished enclosure