Empirical Model of Intracranial Pressure and Head Motion Resulting from a Vibrating Seated Rhesus

A series of experiments was designed to measure the head X and Z accelerations and the intracranial pressure in the unrestrained head of a rhesus monkey. The subject was exposed to a continuum of vibration frequencies from 2 to 35 Hz and peak acceleration amplitudes of 5, 10, 20, and 40 m/s2. The resulting data was used to build a frequency response model relating the head accelerations and pressures to the torso acceleration. The head-to-torso relationships, based upon a single subject, were both repeatable and invariant for torso acceleration amplitudes of 10, 20, and 40 m/s2. At frequencies above the 10Hz, the model strongly suggested the presence of linear system, and the inherent advantages of superposition. The model demonstrates the validity of the experimental method, involving a slow sweep through a range of frequencies, and of the analysis procedures used. More importantly, it promises to be a useful approach to the study of human response to vibration.