The recordings are made on a head measurement system (dummy head) with an 8 channel microphone array. The microphones are connected to a Head Acoustics Squadriga III and they are calibrated to 114dBSPL.

The dummy head is then strapped in to the aircraft to accurately capture the noise field in the cockpit.

Once the recordings are made, they are used in the lab to recreate the sound field. This ensures a repeatable and reliable test environment for the headset measurements.

Some interesting data on levels and frequencies can be obtained from the recordings, I have some rough and ready plots on the analysis page.

Those smart cookies amongst you may have realized that the BlackHawk isn’t commonly used for GA. Whilst you are correct, the plan was that it was going to be used for worst case scenario. However the large sound level in the cabin caused clipping in the recordings rendering them unusable.

Ultimately five recordings were picked for the analysis.

• 172N, takeoff, cruise and landing.

• R44, takeoff at max power and cruise.