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Active noise control to cancel out annoying road noises

Cars can be very noisy machines. Generally, the only thing keeping them from deafening occupants as they drive is a load of low-tech noise-suppressing foam under the bonnet.

Active noise cancellation may make potholes much less of a nuisance.
Active noise cancellation may make potholes much less of a nuisance.

A group of boffins claims to have made strides in noise suppression, however, with a technique known as active noise-control (ANC). This technology works much like today’s noise-cancelling headphones –listening to the noises going on outside and then cancelling them out before they reach your ears.

Without getting too technical, the original sound wave generated by the engine, tyres etc. is analysed and a second, opposite wave is generated and played through the car’s speakers. This new wave acts against the original wave, cancelling — or at least reducing — it in the process.

Noise cancellation technology usually works best with constant low-frequency noises, such as those generated by the sound of an aircraft’s engines or the drone coming from below the bonnet of your Ford Fiesta. However this particular system, developed by Guohua Sun and colleagues of the University of Cincinnati in Ohio, is also capable of filtering out non-uniform, unpredicable sounds of the sort you hear when you hit a random pothole or bump in the road.

Its designers claim the new ANC standard should reduce unwanted noise by at least 50 per cent.

Obviously luxury cars will benefit from quieter cabins, but there are potential drawbacks. The system will no doubt mask the severity of some potholes that are best avoided entirely, causing drivers to plough haphazardly through ruts that might cause damage to their vehicle. Also, if the system proves extremely adept at removing all noise, there’s every possibility careless drivers might run over objects — animals and other road users perhaps – without even noticing.

Ford will be trialling the system in 2013. We’ll be on hand to put it through its paces in due course.

Source: New Scientist 
Image: SimplyGo


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