[Big Dave]

Aviation has had noise-cancelling headsets for over a decade. Much lighter and more effective than heavy sound-deadening material. You are beginning to see snoise-cancelling headsets on target ranges, where hearing loss is a real problem.

I don't think the technology is all that exotic these days.

Might be a real boon for diesels.

Might be a necessity in the beercans we might be driving in the future.