There is some anecdotal evidence coming out of the US, and supported by complaint data that I have seen in Aus, that suggests it is more about visibility than noise.
The rates of noise complaints seem to drop on days when aircraft cannot be seen (ie low cloud cover, fog, smog etc). For example, in the Sutherland area the aircraft are usually about 6000ft. On bright sunny days, there are the normal noise complaints. On cloudy days (ie aircraft in or above cloud) the noise complaints drop.
Yes I know there is one argument that suggests the cloud cover may be acting as an insulator to noise. I cannot argue with this, it sounds logical. But there are currently organisations looking into what the actual source of the complaint is.
Just some food for thought, I offer the following scenario. A few years back John Travolta took his B707 to Melbourne. The outcome of his first approach onto RW16 is well known and was covered on this forum. When he did the go around, most of the noise measuring equipment in west melbourne registered readings of over 100db. The aircraft was in cloud, anyone want to guess at how many noise complaints were made?
My 2 cents worth
Alpha