Widefield acoustics heuristic: advancing microphone array design for accurate spatial tracking of echolocating bats

Area of Science:

• Bioacoustics
• Ecology
• Robotics

Background:

• Accurate 3D localisation of ultrasonic bat calls is crucial for behavioral and ecological studies.
• Existing methods often struggle with complex signal types and source motion.

Purpose of the Study:

• To introduce Array WAH, an open-source simulation framework for designing and optimizing microphone arrays for bioacoustic tracking.
• To evaluate array geometries and identify optimal configurations for bat call localisation.

Main Methods:

• Developed a simulation framework incorporating realistic signal generation, frequency-dependent propagation, and Time Difference of Arrival (TDoA) algorithms.
• Modeled source motion effects, including Doppler shifts, during call emission.
• Compared four array geometries (square, pyramid, tetrahedron, octahedron) across a spatial grid.

Main Results:

• Tetrahedral and octahedral array configurations showed superior localisation robustness compared to planar arrays.
• Planar arrays exhibited limited angular resolution.
• Simulations indicated typical localisation errors of 5-10 cm at 0.5 m arm lengths, constrained by array geometry and signal structure.

Conclusions:

• Array WAH provides a flexible tool for designing field-deployable bioacoustic localisation systems.
• The framework supports the investigation of free-flying bat acoustic behavior.
• Optimized array design is essential for accurate ultrasonic bat call localisation.