The answer is quite subjective and involves a plethora of factors:
1) How loud is the airplane, jet, etc.
2) What time of day (or night) is it flying overhead
3) What direction is the airplane flying in
4) Are there any natural sound absorbers (mountains, trees, shrubbery, freeways)
5) It the property on a raised foundation or a slab
6) Is the property attached or detached
7) Is there attic insulation, dual-paned windows, etc.
8) How acute is the hearing of the person affected by the sound
9) Are there other sounds masking the jet noise (radio, lawn mower, car engine, train, etc.)
10) Check your local airport and the FAA to obtain more info on this subject.
There are seniors living in Leisure Village, Camarillo who are directly below a flight path, and a large percentage of them never notice the air traffic activity sounds.
Actually, you can be near the airport without the plane noise as long as the planes are not traveling directly over your home. Playa Vista has little to no plane noise and is very near LAX while other areas such as Playa del Rey do have some plane noise. The airport has installed dual pane windows and other soundproofing to homes in the area so protect the home owners from excessive noise.
I advise you do spend time in the area you are considering (at least 4 hours) to see for yourself how the noise level is, before purchasing.
As Barry has said, there are so many factors that come into play.
To me, one of the most important factors is the question of whether the home is directly under a flight path. This is apparently important to insurance companies too. I once sold a home near a small, local airport, and the Buyer could not get insurance unless he could prove to the insurance company that the home was not in a direct line with any runway. You can get runway and flight path information from the airport management.
Another factor that's very important is the number of flights. If your airport has a lot of flight schools using it for "touch and go" maneuvers, the airport noise could be constant on certain days and at certain times. So, don't assume that a small airport, without large jets, is necessarily without noise concerns.
Do your due diligence, which includes asking the Seller for a written homeowner's disclosure. Good luck.
Maggie Hawk, REALTOR
Watson Realty Corp.
For example, I live in a neighborhood called Rossmoor, we're sandwiched in the groove of the interchange of the 605, 405 & 22fwys, Plus planes landing at the Long Beach airport are in the distance visible & heard, but they don't fly directly over. I hear the hum of the freeway if my windows are open, like right now, but I don't mind it at all, just used to it.