A German car technology firm has invented a “listening airbag” that can detect the difference between crashes and minor bumps along the road while driving, according to a June 22 CNN.com report. The company, Siemens VDO Automotive, says the "Crash Impact Sound Sensing" airbag works by using sensors that measure vibrations in a vehicle during an accident. The system assesses differing sound waves given off by parts of the car as they crumble during impact. Using the sound waves, the sensors can determine the seriousness of the accident and decide whether or not to deploy the airbag and tighten the seatbelt.Current airbags work by sensing how strenuously the brakes have been applied. The new airbag inflates in stages, depending on the level of deformation, a Siemens VDO spokesman said. The company says the new system would react faster than conventional ones and would also be cheaper.A rival firm, Bosch, is developing a system that detects the weight and position of the passenger before deciding whether or not to deploy, according to the CNN.com report.