Planes at Europe's busiest airport currently descend at an angle of three degrees on their final approach.
But from September 14, an angle of 3.2 degrees will be introduced on a trial basis until mid-March next year.
"The steeper the angle, the less time an aircraft spends at low altitudes, which means that fewer people should be affected by higher levels of noise," airport authorities explained in a briefing document.
"The trial will assess the operational and noise implications of slightly steeper approaches."
It comes as Prime Minister David Cameron's government considers whether to approve a third runway at Heathrow or expand air capacity in southeast England at another airport such as London Gatwick. A decision is expected by the end of the year.
The issue has proved highly controversial, drawing opposition from figures including London Mayor Boris Johnson, partly over concerns about noise in the densely populated area of west London over which many Heathrow flights take off and land.
A commission looking into the issue published a report last month strongly backing a third runway at Heathrow.
(Yahoo News - APF)