IO,
I am not talking about the bog standard dayglo coloured sponge jobs. These are specially designed for the attenuation of all sound, but less attenuation for the voice frequencies. I don't have to change the volume of my headset/intercom since the reduction of other noise means I can hear the radio /intercom more clearly.
To my mind, stopping noise energy getting to the inner ear has to be better than adding to it to cancel it out.
The fancy headsets do sound great, but when testing scientifically in the environment I fly in (which I hasten to add is not sat behind a Lycoming) they do not meet statutory requirements.