Improving ultrasound-based gesture recognition using a partially shielded single microphone

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 utilized 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 utilizes 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 recognition accuracy is increased by 15.3% by utilizing the proposed method.