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. The test articles above are listed in order of increasing body coverage. Insertion loss measurement results for all four PPC test items are shown in Figure 2. The results are not surprising in that the IL of each item increases as the coverage increases and the flanking paths are eliminated. A significant increase occurs with the introduction of the plastic material of the hoods and suits.