An onboard perception system

The present invention relates to an onboard perception system (105) of a vehicle (4) comprising: - a state assessment means (110) adapted to at least assess a state of a first external object (6) located in a vicinity (12) of the vehicle (4) hosting the onboard perception system (105), - at least a first sensor assembly (120) for assessing sound information, and - an evaluation means (130) adapted to evaluate a change in the state of the first external object (6) by using the assessed sound information. The invention further relates to a collision avoidance system (100) comprising such an onboard perception system (105) and to the vehicle (4). Additionally, the present invention relates to a method for evaluating a reason of a change in a state of a first external object (6) located in a vicinity (12) of the vehicle (4) hosting the onboard perception system (105).