Originally Posted by The Nr Fairy
Disadvantages - require integration with headset / helmet, and need careful fitting to ensure comfort for long periods.
Trialled and rejected by MoD in early 90s for exactly the reasons you note. The UK design, if I recall, needed a mould taken of ones ear canal. I believe it was sold to Formula 1 instead, and even they with their huge budgets seem to use sticky tape. An alternative, rejected on cost grounds, was to replace the earshell transducers (cheap and nasty) with a French design (great). The problem is aircrew need to hear audio cues (warning tones etc) and they must be at the correct relative levels. And one must differentiate between ANR for aircrew and for passengers. In many cases, cockpit and cabin.