Using Partially Shielded Microphone for Improving Ultrasound-based Gesture Recognition

Abstract

We propose a method to improve ultrasound-based in-air gesture recognition by altering the acoustic characteristics of a microphone. The Doppler effect is often used to recognize ultrasound-based gestures. However, increasing the number of gestures is difficult because of the limited information obtained from the Doppler effect. In this study, we partially shield a microphone with a 3D-printed cover. The cover alters the sensitivity of the microphone and the characteristics of the obtained Doppler effect. Since the proposed method uses a 3D-printed cover with a single microphone and speaker embedded in a device, it does not require additional electronic devices to improve gesture recognition. We design four different microphone covers and evaluate the performance of the proposed method on six gestures with eight participants. The evaluation results confirm that the recognition accuracy improves from 60.4% to 75.7% on average using the proposed method. We also discuss the velocity of the hand gesture and the effect of the cover for conventional usage of the microphone.