Toyota Using Noise-Cancellation On Crown Hybrid

Toyota is using "active noise control" in its Crown Hybrid model. The system relies on three microphones embedded in the vehicle's interior to detect noise coming from the engine. When engine noise is picked up, three speakers emit sound waves that are 180° out of phase to the noise, providing effective cancellation. This technique is commonly used in noise and echo cancellation.

The always-on system provides an overall interior noise reduction of 5dB to 8dB, and was deemed necessary after the vehicle's engine proved noisier than expected. The system is tuned to provide optimal cancellation at ear-level.

The Crown Hybrid and the Lexus GS  Hybrid share the same hybrid system, but the Crown Hybrid's engine operates at a lower rotational frequency in low-speed driving. The adjustment gives the Crown Hybrid better mileage but creates more interior noise.

Source: Gizmag
Photo: Toyota