A system for characterizing an impact to a user comprising: a sensor assembly configured to measure a linear acceleration and an angular velocity at a sensor position； a data transform component operatively connected to the sensor assembly and configured to represent a location of interest in one of the head and the neck of the user relative to the sensor position as a time-varying function and to calculate an acceleration at the location of interest as a linear combination of the linear acceleration and a cross-product of the angular velocity with a relative velocity between the sensor position and the location of interest； and a system interface configured to provide the calculated acceleration at the location of interest to a user in a human-perceptible form.
