Scattering-free acoustic direction sensor for 3-D sound localization

Sound direction sensing is essential for various applications, including speech recognition, robotics, and surveillance. Conventional approaches rely on microphone arrays that estimate direction based on time or phase differences, but these methods require large spatial footprints for considerable phase difference between microphones. Resonator-based sensors address some of these limitations by leveraging resonant coupling to create direction-dependent responses. However, they are often frequency-dependent and sensitive to environmental conditions, limiting their adaptability. To overcome these challenges, we demonstrate a novel direction-sensing mechanism that emulates acoustic resonance using an electric resonance circuit. This circuit processes signals from two microphones, mimicking acoustic coupling without scattering, as it is not directly exposed to the incident wave. By integrating two pairs of microphones and two coupling circuits, the system enables direction sensing across both elevation and azimuth angles. Furthermore, combining these acoustic sensors with an optical camera creates an acoustic camera, allowing precise source localization within the visual field. This approach enhances spatial sensing capabilities, offering robust and compact solutions for various real-world applications.