If you can afford it always consider am ANR headset first. Much more protection for hearing loss and comfort. I use the Bose, which I find comfortable for long periods and cuts noise induced fatigue.
Re emergency noises or alarms, stall warning etc. Many airlines now mandate ANR(BA, Virgin,RAF Voyager etc.) The noise attenuation is for wind/slipstream and engine noise, completely different frequencies to aural alarms etc.,so no safety worries.
I wish ANR was available earlier in my career, my wife wouldn't keep calling me deaf!!