a flexible diaphragm sealed over the open mouth of {HEAD ~ the housing} to define {TAIL ~ a plenum} between the walls of the mouth in the housing and the diaphragm, and wherein the inlet formed in the housing is in communication with the plenum 
a flexible diaphragm sealed over the open mouth of { HEAD ~ the housing } to define { TAIL ~ a plenum } between the walls of the mouth in the housing and the diaphragm , and wherein the inlet formed in the housing is in communication with the plenum
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH