Generator - 2 ou 4 Strokes ?
All generators produce 'noisy' power. Usually this is adequate for many things, but some things (like TVs, computers or other 'precision' devices) get snotty about it. The only clean powered generators I know about are the 'Inverter' style generators pioneered by Honda and possibly also by Yamaha by now. These put out power which is equal to or better than what comes out of your wall.
All generators tend to be noisy. This is often a problem in campgrounds, and many ban their usage 'at night'. Generators mounted in a sound restricting box (integral or external) are dampened somewhat. Diesel generators may be a bit quieter and definitely last longer due to their slower speed. Again, the Honda EU series generators tend to be the quietest available, due to being completely inclosed and being able to run at a slower speed.