If you have seen a typical industrial-grade generator before, you would know that most of them are quite noisy. That is because they are basically engines (much like the engine inside your car) which employ the principle of internal combustion to produce mechanical energy which the generator then converts to electrical energy.
Internal combustion engines, by their very nature, can produce a significant amount of noise. Depending on the design, a generator can produce noise that could be loud enough to disturb you and those in the vicinity where it is running. If you live in an area where peace and quiet is highly valued, a noisy, whirling sound of a generator will surely cause some problems.
As a matter of fact, some localities may have ordinances or regulations that prohibit equipment such as generator noise so if you go start operating a generator, be sure to check the noise rating before you do.
If you want to please your ears and those of your neighbors, it might be a good idea to get a generator designed for low-noise residential application. These generators, through some innovative techniques, have become less noisy. Techniques vary but most employ muffling techniques by encasing the generator in a noise-reducing enclosure that may or may not use sound-damping material and body designs. The most effective way of reducing noise is by controlling the speed of the engine. A slower engine means lesser noise so some generators, particularly inverter generators, have been designed to vary engine speed depending on the load. Along with clever enclosure designs, inverter generators have found good ways to reduce noise to sub 30 dB (A) levels for the smaller 1000 watt generator models and lower.
Is noise a factor? The answer is not straight forward but if you plan on using the generator in any recreational or residential application, noise definitely is something to seriously consider in your buying decision.