These are about $9 on Amazon, have only about 12db of noise attenuation, which is just enough to take the edge off the sound level in flight and still allow me to hear to the other pilot and the audio speaker to heat ATC. Flat frequency attenuation so sounds still present pretty naturally, just a little softer. Added benefit of not looking like some sort of fashion accessory. Cheap enough that I don't lose sleep if I misplace them.

https://www.hearos.com/collections/m...with-free-case