Toyota has employed the ‘Active Noise Control’ system on its Crown
Hybrid vehicle, using three microphones located on the roof of the
interior of the car to detect the muffled noise of the engine.
The system then generates antiphase signals from three speakers, two
located on the right and left front doors and one rear woofer on the
rear shelf, to counter the noise. The system which was implemented
after the car’s engine was found to be noisier than expected, reduces
the interior engine noise by about 5 to 8dB, the company said.
“We collected the data such as the distance between the microphone
and the head of a passenger, the distance between each speaker and the
head of a passenger, and the shape of a car interior,” Toyota said.
