Auditory Warnings and Rotor Noise

[400 Hertz]

Try a look at http://www.racal-acoustics.co.uk/english/voice.htm they are into all sorts of noises! These are fitted on N Sea helis.

My experience is that the biggest noise in the aircraft is the whining that the pilot makes in the line office "Moan, moan, moan!".


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400 Hertz but DC is easy