The Natural Sound Smoother, the world's first technology that significantly reduces diesel knock sounds was newly developed by Mazda Motor Corporation. They announced that they will mount it on the SkyActiv-D 1.5 that will be equipped in the CX-3, which will be released from the end of February.
As a result of research on identifying the mechanism that creates the diesel knock sounds, Mazda has found that the vibration of the generating piston is the cause. By installing within it the hollow piston pin, the newly developed Natural Sound Smoother will absorb the vibration causing the knocking sound
Therefore, the diesel knock sound, that is around 3.5kHz frequency, heard inside the vehicle during start up and slow acceleration is reduced by 10dB at maximum; this is compared to vehicles not equipped with the same device. The results are engine sounds that feel more pleasant and a higher degree of quietness when driving around the city.