Acoustic Imaging Using the Built-In Sensors of a Smartphone

Thanks to the rapid development of the semiconductor industry, smartphones have become an indispensable part of our lives with their increasing computational power, 5G connection, multiple integrated sensors, etc. The boundary of the functionalities of a smartphone is beyond our imagination again and again as the new smartphone is introduced. In this work, we introduce an acoustic imaging algorithm by only using the built-in sensors of a smartphone without any external equipment. First, the speaker of the smartphone is used to emit sound waves with a specific frequency band. During the movement of the smartphone, the accelerometer collects acceleration data to reconstruct the trajectories of the movements, while the microphones receive the reflected waves. A microphone plus an accelerometer are able to partially replace the functionality of a microphone array and to become a symmetry-imitation system. After scanning, a series of algorithms are implemented to generate a heat map, which outlines the target object. Our algorithm demonstrates the feasibility of smartphone-based acoustic imaging with minimal equipment complexity and no additional cost, which is beneficial to the promotion and popularization of acoustic imaging technology in daily applications.