July 15, 2008 Toyota has taken the principle behind noise-canceling headphones and applied it to its Toyota Crown Hybrid . The companys Active Noise Control system uses three microphones located on the roof of the interior of the car to detect the muffled noise of the engine and 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 cars engine was found to be noisier than expected, reduces the interior engine noise by about 5 to 8dB, the company said.

Although equipped with the same hybrid system as the Lexus GS, the engine of the Crown Hybrid has a lower rotational frequency at low speed which results in better mileage, but also more noise.... // Gizmag