Why is there the single dwelling limit with the airport overlay?

Those of you who have bought in Hume council (Melb) are probably aware of the Mae01 and Mae02 airport environs overlays that are on a lot of the blocks within Coolaroo, Dallas and Meadow Heights etc.
I am perplexed as to why there is the single dwelling limit?
All I can seem to find is this is to limit the noise from the planes, however what difference does it make if there is 1 or 3 dwellings on a block? I don't see how the number of dwellings has any impact on the noise at all?
I wonder if these dwelling restrictions will ever be lifted when populations increase and they need to free up more land?
I am really interested to know the reasoning behind this, if anyone actually knows Im interested to hear!

 

Generally because they don't want more people living there who will complain. I know that sounds silly but it's the actual reason.
Even though they buy knowing there is a airport and noise there they won't actually understand it so they restrict development in all states in these areas.
Infill increases solid surfaces like driveways, walls and roofs which will bounce the sound around more and decrease sound absorbing things like trees and soft landscaping.
In some Perth areas we have Quiet House design where new owners who build must use more insulation, thicker glass and bedrooms placed away from the noise to reduce impact on inhabitants.

 

In the next suburb?

 

That is a really poor excuse isn’t it? And then we hear that there’s housing shortages and affordability issues due to lack of land near cities! Crazy

 

One of Melbourne's great assets is a curfew-free airport. It would be tragic if increasing development near the flight paths led to this being placed in jeopardy.

 

Perth is the same. Runs 24hrs which causes a lot of noise complaints especially at night but they try and vary the night time routes to share the "joy"

This is the Perth planning guidelines for around the airport State Planning Policy 5.1 Land Use Planning in the Vicinity of Perth Airport

 

Lol Quiet House Design is generally for housing being built near busy roads. So they have restrictions on bedroom placement - must be at the rear.