Measure the room ambient noise levels. The use of a single microphone in steps 1b and 4 are for consistency and control checks on the diffuse sound field. Steps 1a and 4b are used to ensure that the ambient noise levels are not influencing the measurements. All measurement are performed without interruption. The data gathered using this procedure allows for statistical averaging and analysis of the sound field, the IL of the PPC, and IL variation due to donning or fit.
Hoods cover the ears, hair, and neck, with a tapered fit for head and neck.
Hood is gathered below the chin with a hook and loop fastener. The head cover portion of the hood is a 20 mil clear PVC cylinder with a 14 mil opaque PVC plenum. An integrated 6 mil clear PVC cape covers the wearers shoulders. Gloves attach to the top to seal the arms. Tyvex collars located inside suit top seal around the body with elastic bands at neck and mid-chest.