Managing Noise With Noise?
Can one noise actually cancel out another? The Airport Authority and the University of British Columbia (UBC) are looking at this possibility to help manage aircraft noise at YVR.
Eliminating noise by producing an opposite sound (equal in amplitude but opposite in phase) is known as Active Noise Control (ANC). This technology is already successfully used in enclosed spaces such as heating ducts and aircraft cabins. ANC-equipped headphones are used by pilots of propeller-driven aircraft to reduce low-frequency background noise, allowing them to hear conversations and warning signals in noisy cockpits.
The outdoor environment, however, presents several challenges for ANC technology. From temperature and weather fluctuations to uncontrolled background noise, successfully using ANC outdoors is extremely difficult.
Since 1997, the Airport Authority's Environment Department has been working in collaboration with UBC and the airlines to investigate whether ANC can be used to mitigate noise from ground-based engine run-ups. Engine run-ups are maintenance tests performed on aircraft engines and systems to ensure they are functioning safely before the aircraft is put back into service.
Every two years, a UBC graduate student from the Department of Mechanical Engineering is selected to participate on the project as part of his or her thesis.
Recent field tests at the airport have focused on quantifying the noise characteristics of aircraft performing run-ups, and noise measurements have been done on two propeller aircrafts, donated by Central Mountain Air and Air Canada Jazz, along with a larger Air Canada Jazz Regional Jet. ANC research has focused on propeller aircraft because their run-up noise signature tends to make them ideal ANC candidates. This is because the sound created by these aircraft is simple in tone, making it easier to find a counter tone to balance the noise.
While the research is ongoing, the work has resulted in computer simulation models, comprehensive reports, and laboratory experiments which continue to add valuable information to the possible application of ANC technology. Despite these gains, there are still significant hurdles to overcome before a working system can be realized.
Managing airport noise to balance the community's desire for safe, convenient, 24-hour air travel with enjoyable urban living is the Airport Authority's commitment to our neighbouring communities.
For further information on ANC research, please contact the Airport Authority's Environment Department at firstname.lastname@example.org