Since the airbag passive restraint system may be in general use in early 1976, and in fact is now an option on some automobiles, its potential biomedical hazards need to be thoroughly examined. Previous investigations in this area have been extermely limited.

The objective of this study was to investigate the effects of local slap pressure of airbag deployment against the external ear and tympanic membrane and to measure its effects on subsequent hearing acuity. Adult and infant squirrel monkeys were used as experimental subjects, because the gross structure of their ear and tympanic membrane closely resembles man's. To create an adequate simulation of the airbag trauma, a small airbag was fabricated and mounted on a pneumatic impact facility. This device was designed to produce a specific velocity to determine the behavior of objects under impact conditions simulating accident kinematics. Cochlear nerve action potentials were measured in both ears of 10 subjects prior to blast, immediately postblast, and several weeks postblast. Highspeed photography recorded the events of the blast, as well as the technique of recording the potential from the cochlea and the appearance of the drumhead pre- and posttrauma. No permanent hearing damage, eardrum perforation, or disruption of ossicles occurred at airbag velocities up to 100 mph and a sound intensity level of 150 dB.