Validation of Earplug Accelerometers as a Means of Measuring Head Motion

To test whether earplugs used by IRL and CART accurately measure the head accelerations under impact conditions, manikins and human volunteers were impacted on the AFRL Horizontal Impact Accelerator (HIA) up to -10 Gx, and 150 ms duration. Manikin heads contained 3 linear and 3 angular accelerometers while the humans used a bite bar containing 3 linear and one (Ry, pitch) angular accelerometer. Each subject wore the custom made instrumented earplugs. Wavelet analysis showed that the head accelerations during the primary response were linearly correlated with left and right earplugs at from .964 to .991. The earplugs provide a good measure of primary head acceleration.