The “Tridimeter”: Engineering New Ways to Study the Sounds of Nature

Dr Chandler situated his research within the context of the Anthropocene, the current era in which human activity has become the dominant influence on the Earth’s climate, ecosystems and landscapes. He highlighted accelerating ecological degradation and the intensifying climate crisis, illustrating the scale of impact with the example that the plastic bottles discarded globally each year would, if stacked, wrap around the Earth approximately 5,000 times. This underscored the magnitude of human influence on climate and biodiversity.

He then referenced the work of Bernie Krause, whose research documents the loss of biophony, the collective sound of living organisms, increasingly replaced by human-generated noise, or anthrophony, and in some cases silence. Through long-term acoustic recordings, Krause demonstrated how reductions in environmental sound reflect ecosystem stress and biodiversity decline. As he observes, “the rising silence speaks volumes”, reminding us that when the sounds of nature diminish, it signals more than quiet; it signals loss.

A particularly engaging moment explored human echolocation, noting that a small number of individuals worldwide are able to perceive their surroundings acoustically. This provided a compelling parallel to how bats “see” the world through sound and reinforced the importance of advancing acoustic monitoring technologies.

The lecture then turned to bats, which are ecologically significant yet methodologically complex to study. With over 1,400 microbat species worldwide, alongside megabats, and seven species present in Gibraltar, these mammals rely on ultrasonic echolocation to navigate and hunt.

Through a live demonstration, Dr Chandler showed how conventional bat detectors function. While capable of identifying ultrasonic calls and confirming species presence, they cannot determine precise three-dimensional location or reliably distinguish how many bats are present. Researchers can detect bats acoustically but cannot accurately “point” to where they are in space, making robust population estimates difficult.

Drawing on gaps in the literature, Dr Chandler highlighted the absence of effective three-dimensional tracking techniques for bats in flight in real time. He introduced the mathematical foundations of his approach, demonstrating how trigonometry, sound propagation modelling and multi-sensor triangulation can be applied to ultrasonic signals. By analysing time-of-arrival differences across microphone arrays, he developed a novel algorithm capable of estimating bat positions in three dimensions.

Dr Chandler then described the development of the “Tridimeter”, an innovative acoustic tracking system developed during his PhD and designed to move beyond simple detection towards accurate spatial localisation of bats and improved counting precision. Using field data and video, Dr Chandler demonstrated the proof-of-principle, showing how bat trajectories could be visualised in real time within three-dimensional space.

The lecture concluded with reflections on future directions for the Tridimeter system, including enhanced sensor precision and further algorithmic refinement. Overall, the research exemplifies how interdisciplinary innovation can strengthen ecological monitoring and contribute to more robust conservation science in a rapidly changing world.