Testing Shows How a 'Hearing Car' Can Enhance Self-Driving Capabilities

Test shows external microphones may help automated vehicles recognize sounds such as emergency vehicles or pedestrians.

July 3, 2025

2 min read

The test vehicles of Fraunhofer IDMT and Cariad SE are on the road to test new sensor and measurement technology in ice and snow in Sweden.

Cameras, lidar, and radar have been around a long time to detect other vehicles, road signs, and painted lines as part of ADAS features, including automated driving. But the ability to detect outside noises, such as pedestrians or an emergency vehicle's siren, had been absent. That may change.

The Fraunhofer Institute for Digital Media Technology - Oldenburg Branch for Hearing, Speech, and Audio Technology is researching the integration of acoustic sensor technology in the KI4BoardNet project with The Hearing Car. The team equipped research vehicles with new microphones and specially developed measurement technology to help automated cars recognize external noises.

A test was conducted in Sweden with project partner Cariad SE, the Volkswagen Group's automotive software company, to determine how the new measurement technology performs in terms of reliability and usability. The researchers wanted to find out how the microphones perform under different weather conditions and degrees of contamination. Initial analyses of data from road tests under various conditions – snow and ice, heat, and wet weather – show positive results.

Fraunhofer measurement technology integrates into a vehicle to enable researchers to easily adapt the technology to individual needs.

“Our tests show that exterior microphones can change the way we interact with our cars and, in combination with optical sensors, improve safety for automated driving functions,” said Hagen Jaeger, product owner Exterior Acoustic Perception at Cariad.

The technology development for The Hearing Car is funded by the Lower Saxony Ministry of Science and Culture, the Volkswagen Foundation in the “Vorab” program, and the Federal Ministry of Research, Technology, and Space in the research project “Integrated agile E/E development for merged and standardized energy and data networks,” or KI4BoardNet for short.

KI4BoardNet seeks to develop the architectures, components, and design tools for the vehicle electrical system of the future. The project involves joint research, the implementation of dynamic, AI-supported design processes, and automation in the development and production of vehicle electrical systems.

Fraunhofer IDMT is publishing documentary videos on its LinkedIn page here to document the journey of The Hearing Car to Sweden. For more information, visit the Fraunhofer IDMT website here.