Message posted by Magoo on June 07, 2000 at 20:58:16 EST:

I know this has been trialled aboard helos, but I heard there were some vibration issues that had to be overcome.

You're right when you say cars (e.g. Lexus, Mercedes, BMW) use this active noise to insulate their cars, but this is for the comfort of passengers inside the vehicle who are sitting in a generally static position at which these sound waves can be directed. Similarly, headsets and such are worn in a static position on your head, and therefore the noise suppression can be directed accordingly.

Masking or supressing the exterior noise made by a helo or any other vehicle is a whole new can of worms, as it must be directed in 360 degrees and three dimensions in order to cover all potential 'listeners'.

Whilst it may be possible to partially suppress the sound of an engine or other machinery using such active sound methods, as Richard mentioned previously, the rotor blades cause most of the noise of a helo, and this would be extremely difficult if not impossible to mask effectively.

Magoo

In Reply to: Re: What type of helicopter was it? posted by Shoe on June 07, 2000 at 17:55:38 EST:

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