Cancelling Intermodulation Distortions for Otoacoustic Emission Measurements with Earbuds

This paper presents a novel cancellation method of Intermodulation Distortions (IMDs) for earbud speakers used to measure Distortion Product Otoacoustic Emissions (DPOAE). Speakers’ non-linear behaviour is a significant problem for earbuds with small loudspeakers due to limitations in cone movement. Linear and non-linear speaker modelling enables us to inject exact distortion inverse to cancel what is introduced by speakers’ non-linearities. Our proposed method is compared against state-of-the-art related works in terms of harmonic reduction ratio. Simulation results and evaluation on real hardware show a 77% to 95% reduction in the harmonic distortions of a focused frequency region at the output of the loudspeaker, outperforming existing works by 6% to 14%.