Estimating Ear Canal Volume Through Electrical Impedance Measurements From In-Ear Headphones - Initial Results

The acoustics of the external ear has been extensively studied in areas such as audiology and 3D audio. In other contexts, electrical impedance measurements found application in the analysis, design and performance control of electro-acoustic transducers. This research investigates the links between ear canal acoustics and electrical impedance of in-ear headphones. The primary goal was to examine the effect of the ear canal dimensions on impedance and pressure at the eardrum. Impedance and pressure were measured using ear canal simulators of different size and shape. Results show similarities between the two quantities, with a clear relation between main resonant peak and volume. This paper gives insights into the potential use of electrical impedance to extract information about the external ear.