Airbag noise measurements

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Airbag noise measurements

Rasmussen, Per / Nielsen, Kim N.

The noise emitted during an airbag deployment is characterized as both an impulse with high frequency content and a pressure increase inside the vehicle compartment with low frequency content. While the determination of the low-frequency pressure signal is easily done using a standard microphone with a suitably low cut-off frequency, the measurement of the high-frequency content needs careful selection of microphone, preamplifier and data acquisition system. When an airbag inflates rapidly during a car accident, the driver is exposed to a large impulsive sound pressure wave of short duration that could possibly damage human hearing. The time signals of these impulsive sounds were measured using transducers of various types and sizes in order to investigate the repeatability of measured results both for each transducer and between transducers. The aim was to find a suitable way for manufacturers to test airbags and to be able to make meaningful data comparisons. Measurement of the steep impulse of an airbag deployment requires a small transducer able to handle very high frequencies A 1/8-inch measurement microphone has the size and frequency range capability to measure the very short wave fronts and capture the high frequencies The use of high speed simultaneous sampling and effective data processing tools enables detailed investigation of the signal and correlation with the physical phenomena and high speed recordings.