75% Quieter Engines: The Noise Reduction Tech That’s Changing Airport Neighborhoods

Stand near any major airport today and you’ll notice something different from a decade ago – it’s quieter. Much quieter. The jet engines powering modern aircraft produce up to 75% less noise than their predecessors, a transformation that’s reshaping communities around airports worldwide and enabling flights that would have been impossible under older noise regulations.

The Science of Silence

Aircraft engine noise comes from two primary sources: the high-velocity exhaust gases exiting the engine and the spinning fan blades at the front. Engineers have attacked both problems with increasingly sophisticated solutions.

The most visible advancement is the dramatic increase in engine bypass ratio – the amount of air that flows around the engine core versus through it. Modern high-bypass turbofan engines like the GE9X (powering the Boeing 777X) and Rolls-Royce Trent XWB (on the Airbus A350) push bypass ratios above 10:1. This means over 90% of the thrust comes from relatively slow-moving air pushed by the fan, rather than high-speed exhaust gases. Slower air means less noise.

Chevrons: The Serrated Edge Revolution

Look closely at the engine nacelles on newer Boeing aircraft and you’ll see distinctive serrated edges called chevrons. These saw-tooth patterns at the back of the engine nacelle mix the high-speed exhaust with slower ambient air more gradually, reducing the turbulent noise that occurs when these airstreams collide.

Boeing pioneered chevron technology on the 787 Dreamliner, and the results were dramatic:

• Takeoff noise reduced by approximately 60%
• Approach noise cut by up to 50%
• Significantly smaller noise footprint around airports

The technology has since spread across the industry. Even retrofit chevron kits are now available for older aircraft, allowing airlines to reduce noise on existing fleets without purchasing new planes.

Advanced Acoustic Liners

Inside modern engine nacelles, specialized acoustic lining materials absorb sound waves before they can escape. These honeycomb-structured panels work like sophisticated soundproofing, targeting specific frequencies that are most annoying to human ears.

NASA’s research into “zero-splice” acoustic liners – continuous panels without gaps – has shown potential for an additional 2-3 decibel reduction. While that might sound modest, decibels are logarithmic: a 3 dB reduction represents cutting perceived loudness nearly in half.

Community Impact

For communities near airports, these noise reductions have been transformative. Properties that were once considered unlivable due to aircraft noise have seen values increase. Schools that required soundproofing can now operate with windows open. Sleep studies show measurable health improvements for residents near airports that have transitioned to quieter fleets.

Consider London Heathrow, one of the world’s busiest airports located in a densely populated area:

• The number of people within the 57 dB noise contour dropped from 258,000 in 2006 to 126,000 in 2023
• Night flight restrictions have been relaxed for the quietest aircraft
• Property values in previously affected areas have increased 15-20%

Enabling New Operations

Quieter engines don’t just benefit existing routes – they make entirely new operations possible. Airports with strict noise curfews, like Sydney’s ban on flights between 11 PM and 6 AM, are reconsidering these rules for aircraft that meet new noise standards.

Airlines are using their quietest aircraft strategically. Delta positions its newest A350s and A321neos on routes to noise-sensitive airports, gaining competitive advantage through access to off-peak slots that older aircraft can’t use.

The Geared Turbofan Breakthrough

Pratt & Whitney’s Geared Turbofan (GTF) engine, used on the Airbus A220 and A320neo family, represents perhaps the biggest noise reduction advancement of the past decade. By adding a gearbox between the fan and the low-pressure turbine, the engine allows each component to spin at its optimal speed.

The result: the fan can be larger (quieter) while the turbine spins faster (more efficient). GTF-powered aircraft are measurably quieter:

• 75% smaller noise footprint than previous generation engines
• Meets the most stringent Stage 5 noise standards with margin to spare
• Enables operations at noise-restricted airports like London City

What’s Coming Next

Engine manufacturers are already working on the next generation of noise reduction technology. CFM International’s RISE (Revolutionary Innovation for Sustainable Engines) program aims for an open-fan design that could reduce noise by another 20% while cutting fuel consumption by 20% as well.

Airbus and Boeing are also exploring aircraft configuration changes – like engines mounted above the wing or at the tail – that could shield communities from engine noise during takeoff and landing.

The Quiet Future

For passengers, quieter engines mean more comfortable flights with less cabin noise. For airlines, they mean access to more airports and operating hours. But the biggest beneficiaries are the millions of people who live near airports – communities that can finally enjoy peace and quiet even as air traffic continues to grow.

The 75% noise reduction achieved over the past two decades represents one of aviation’s greatest environmental success stories. And with new technologies on the horizon, the industry is far from finished making flying quieter for everyone.