Acoustic test fixtures (ATFs) are often used to predict sound reaching the auditory system for potentially hazardous exposure scenarios. Although ATFs allow for repeatable testing in high-intensity sound fields, they do not adequately capture the complex physics of sound propagation through human tissue and bone. A commercially available head surrogate was used to quantify air conduction (AC) and bone conduction (BC) pathways of sound propagation to the inner ear. This surrogate contained accelerometers to quantify the BC component of the signal and microphones at the termination of the ear canals to quantify the AC portion of the signal, intending to yield more biofidelic measurements of high-amplitude noise exposures than those provided by conventional ATFs. However, BC stimulation can also arise from lower-amplitude signals produced by purpose-built transducers (e.g., BC communications systems) placed on the surface of the head. Thus, to extend the capabilities of the AC/BC ATF platform, additional sensors were identified for incorporation into the head surrogate; a force-sensing capacitor was selected for static force characterization and a PVDF force sensor was selected for dynamic force characterization. The combination of BC-compatible head surrogate and surface force sensors allows for more comprehensive characterization of complex sound transmission pathways.
Reeser et al. (Wed,) studied this question.