Saint, quite right, but a very brief summary of my experience.
In 1962 we were told not to wear our helmets as we could not hear a shouted warning.
In 1963 it was SOP to wear service headdress to the aircraft.
In 1974 we wore headphones with noise attenuation.
In 1978 we had a trial of noise attenuation.
In 1981 we had noise attenuation headsets.
In 1991 it was mandatory that we wore headsets on the dispersal.