Predicting sound localization with an air and bone conduction capable acoustic test fixture

Hearing protection devices (HPDs) degrade the user’s ability to accurately localize sound sources. The extent of this impact has been assessed via human subject testing. Human perceptual studies are expensive and time consuming, so augmenting these results with analogous measurements in acoustic test fixtures (ATF) is advantageous. In a previous study, we utilized an ATF equipped solely with microphones to predict the effects of HPDs on sound source localization seen in human subjects. However, these experiments only consider the air-conducted component of sound (AC); bone-conducted(BC) sound was not measured or otherwise accounted for. A more biofidelic ATF that is capable of accounting for BC sound may improve the accuracy of these predictions. Here, we repeat electromechanical measures using an ATF with increased biofidelity that incorporates multiple sensors—microphones (measure AC transmission) and accelerometers (measure BC transmission). For an 85 dB SPL source, accelerometers were able to detect impinging sound bilaterally, with source location-dependent variation of measured sound features, including bilateral timing and level disparities. By improving ATF biofidelity and incorporating the effects of BC sound transmission into the existing AC localization predictions, we aim to improve estimates of human localization performance degradation due to HPDs.