jinman,
As I recall, you wanted to post the sound of a NH engine. I will let Muhammad worry about copyright infringement, but let me pose two hypothetical situations.
If NH has copyrighted the sound of its engines, then they could sue anyone who infringes that copyright by reproducing that sound. However, if they havent copyrighted the sound of their engine, then you could. Then, you could sue NH or anyone else who fires up a NH engine and makes your copyrighted noise.
Sounds like a good business opportunity. Like cybersquatting.
Or is it really just a flat tire.