Sorry to take so long to reply, hard drive melted! We operated the 115C and the E model, one with two blade fixed pitch, the other with three blade C/S prop, back pack chutes, no hard hats.I did my time in the back seat of Harvards and both seats on the B25 instructing, now they were noisy! I always used ear plugs in these aircraft, also plugs, hard hat and ANR when spraying in the Ag Cat, my wife says my only hearing loss is "selective", such phrases as "take out the garbage" "plow the snow" seem to get lost between ear hole and brain!