In Car rattle noise management

Overview & Synopsis

Rattling is an audible and unwanted noise radiated by structures and objects mechanically or acoustically linked to the loudspeakers. The study presents a system of digital processes to prevent rattling that suppresses or reduces rattling whilst retaining the original perception of low frequency energy. The principle is to generate low frequency harmonics which are subsequently added to the original signal. The loudspeakers are able to reproduce the harmonics correctly, before the rattling frequencies are removed. Thanks to the psychoacoustic effect known as the missing fundamental theory, the listener perceives a good low frequency rendering without being disturbed by the rattles. The tasks are carried out in the following order: (1) Identify the frequency bands at which rattling occurs, (2) Use a low-frequency band to generate harmonics (including the rattling frequencies), (3) Add the harmonics to the original signal, (4) Remove the energy at the frequencies which are causing the rattling. By using this method, the bass rendering can be improved by avoiding rattle noise and pushing the loudspeaker into the low frequencies that the speaker or the doors cannot handle.