An mm-sized biomimetic directional microphone array for sound source localization in three dimensions.

Area of Science:

• Bioacoustics
• Microelectromechanical Systems (MEMS)
• Sensor Technology

Background:

• The auditory system of the Ormia ochracea fly is a well-established model for subwavelength directional sensing.
• Previous research has primarily focused on 2D directional sensing, with limited exploration of 3D sound source localization.

Purpose of the Study:

• To investigate the efficacy of Ormia ochracea ear-inspired piezoelectric MEMS microphones for 3D sound source localization.
• To develop and validate a mm-sized array capable of sensing sound from X, Y, and Z axes.

Main Methods:

• A mm-sized array of three biomimetic MEMS directional microphones was designed and fabricated.
• Microphones were arranged with a 120° angular rotation to achieve 360° coverage in the azimuth plane.
• Analytical simulations and experimental measurements in an anechoic chamber were conducted.

Main Results:

• The array demonstrated accurate 3D sound source localization, with results from simulations and experiments showing compliance.
• High angular resolution was achieved: ±2° at the normal axis, ±1.28° in the azimuth plane, and ±4.28° in the elevation plane.
• The cosine-dependent horizontal component of sound was identified as a cue for Z-axis directional sensing.

Conclusions:

• The Ormia ochracea ear-inspired MEMS microphone array effectively enables 3D sound source localization.
• This work provides a foundational understanding for advanced bio-inspired acoustic sensing systems.
• The study highlights the potential for biomimetic sensors in complex acoustic environments.