Plug some Bose-X headets into an R44 and BINGO! turns your piston engine heli into a smooth multi-million pound sound proofed wonder!!
If you are enthusiastic about flying I would say they are THE accessory for your Xmas stocking. They are so light, and cut out all the unwanted noise, but let the important noises through!
I have 4 battery portables, always keep spare AA batteries under the seats and ensure you change them every 25 hours of flying....