Scientists say they can banish those unwanted sounds of the city

For those who live in the increasingly hectic metro areas around South Africa and the rising number of homes along our busy highways, the sound of traffic if far from music to our ears.


In fact, international studies have shown that it can make you extremely ill and can even lead to death. No, the noise itself won't kill you. But the associated stress and anguish – sometimes undetected at a conscious level – exacerbates underlying conditions such as heart disease and type two diabetes.


The European Environment Agency, for example, blames 10,000 premature deaths, 43,000 hospital admissions and 900,000 cases of hypertension a year in Europe on noise. The most pervasive source, it says, is road-traffic noise (Noise in Europe 2014 report).

Let the breeze in but not the traffic noise


But now help is at hand and you may soon be able to open your window to let the breeze in and the cat out, while the cacophony of traffic noise from the busy main road miraculously remains outside.


A collaboration of scientists from the UK, Singapore and Japan has this month published a study in the Scientific Reports section of the academic journal Nature, in which they describe how they developed and fitted an "active sound control system" into the opening of domestic windows in an effort to reduce or eliminate incoming sounds.


"Active sound" is when a microphone detects an incoming sound and then uses loudspeakers to emit a sound of the same frequency but with an opposing pressure pattern. The two then cancel each other out and the unwanted sound does not enter the room.

Results the same as if the window was shut


The results, the scientists found, were better than what would be achieved by "a fully shut single-glazed window in ideal conditions".


In other words, the open window let in no more sound than if it had been properly closed by the occupant of the room.


"We have proved that it is possible, using loudspeakers in a window, to significantly reduce the sounds that come through an open window," said Prof Stephen Elliott, of the Institute of Sound and Vibration Research at Southampton University and a co-author of the research.

System cannot yet combat all outside sounds


It is worth noting, though, that at this stage the system cannot shut out all sounds at all frequencies. It works best when the sounds are at low frequency in the 300Hz and 1kHZ range.


Fortunately, this is the range at which sounds such as traffic and train noise occur.


"If you can reduce that low frequency noise that really distracts you from whatever you are doing, then that is obviously a help," Elliot said.


He added that further work needs to be done on refining the system. A commercially viable system could be available to consumers in five to 10 years, he estimated.


Also read: Google incorporates AI noise cancellation feature for G Suite users


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