Velocity/Pressure Dual-Sensing Probe for Acoustic Measurements in the Human Ear Canal

About This Grant

PROJECT SUMMARY This research aims to pioneer a dual-sensing ear canal probe that simultaneously measures acoustic pressure and particle velocity, enabling accurate, reliable, and user-friendly assessment of otoacoustic emissions and middle-ear reflectance—critical for evaluating peripheral auditory function. Current ear canal acoustic probes, which rely solely on pressure microphones, suffer from inaccu- racies and noise. A major limitation is the inability of pressure-only probes to capture sufficient information to determine ear canal wave behavior—leading to sensitivity to probe positioning and the need for complex calibra- tion, and ultimately resulting in inaccuracy, unreliability, and poor usability. Our approach adds acoustic particle velocity sensing to conventional pressure measurement. This dual-sensing approach enables accurate charac- terization of ear canal acoustic waves in a single measurement, significantly improving consistency and reliability while simplifying calibration. Another challenge is that ear canal signals are often extremely faint—near the noise floor of today’s miniaturized microphones. Our method can detect otoacoustic emissions at least 10 dB quieter than state-of-the-art systems, reducing averaging time required to extract these signals from noise and enabling detection of even quieter signals. This capability is especially valuable in hearing diagnostics and research. This work builds on our recent discovery that the orb-weaving spider uses its web as an external auditory sen- sor, capable of detecting acoustic particle motion with mechanical sensitivity that surpasses all known eardrums. Inspired by this remarkable natural mechanism, we propose to engineer a transformative acoustic velocity sens- ing technology that directly addresses the physical limitations of existing pressure-based ear canal probes. In Aim 1, we will create a bioinspired mechanical sensing element that detects acoustic particle velocity, uniquely com- bining ultrahigh mechanical sensitivity—approaching the maximum physical efficiency—with ultra-low thermome- chanical noise, beyond the reach of conventional pressure sensing. In Aim 2, we will innovate an ultra-low-noise optomechanical velocity sensor by transducing the motion of the mechanical element using laser interferometry, renowned for its unmatched sensitivity. This new class of velocity sensor will then be integrated with a minia- ture pressure microphone to produce a compact, first-of-its-kind velocity/pressure dual-sensing probe. In Aim 3, we will rigorously validate the dual-sensing probe performance through comprehensive ear canal acoustic measurements in individuals with normal and impaired hearing. By simultaneously measuring both acoustic particle velocity and pressure, the proposed dual-sensing probe will set a new benchmark for accuracy, sensitivity, speed, and clinical utility in ear canal acoustic measurements. This novel tool has the potential to transform auditory research, enhance hearing diagnostics, and improve the evaluation of auditory treatments—marking a significant advancement in the field.