The Next-Generation Air Transportation System (NextGen) will most likely bring more aircraft noise to Southern California. Residents of Mar Vista, Culver City, Santa Monica, and Pacific Palisades already are noticing jets flying in and out at lower altitudes and more often. This is because the NextGen system uses satellites instead of air traffic controllers for precision separation of aircraft, allowing them to fly at lower altitudes and much closer together for landings and departures. Click below for an interactive map of possible noise level changes.
An article and video about it can be found here.
Also, check out this study that was done on FAA noise data for the SoCal area: