EV Testing and Ultrasonic Challenges in VSAC — Strategies for high-frequency measurements using omnidirectional sources and optimized placement —

08/16/2025

MFAC / MSAC

Introduction: New Sound Sources in the EV Era

As automotive electrification advances, traditional engine noise is being replaced by new types of sounds such as inverter whine, motor drive noise, and warning sounds like AVAS.
These sounds often include high-frequency components, making it essential for Vehicle Semi-Anechoic Chambers (VSAC) to accommodate ultrasonic and high-frequency testing environments.

Requirements for Ultrasonic Measurement Environments

  • Testing frequency range extending to 10–40 kHz and beyond
  • Even so-called omnidirectional sources become directional at high frequencies, making source placement critical
  • Proper microphone positioning and reflection control are essential, based on ISO 3745 and ISO 26101 guidelines

Additionally, self-driving and ADAS applications require measurement of sensor emissions and ultrasonic noise, making floor reflections and ceiling absorption important considerations.

Optimizing Omnidirectional Sources: Using HBK’s Dodecahedron Speaker

To maintain near-omnidirectional behavior even at higher frequencies, several strategies are used:

  • HBK’s dodecahedron speaker with frequency-tuned output
  • Placement at no more than 150 mm from reflective surfaces, as recommended in ISO 3745:2012
  • In some cases, embedding the source in the floor or wall to minimize reflections

Sonora’s VSAC Design: Leading the Way in EV Testing

At Sonora, our VSACs are built to meet the needs of modern electric vehicle acoustics:

  • High-frequency absorption using BFW ceiling modules
  • Flat absorber structures optimized for ultrasonic performance
  • Support for combined pink noise and pure tone testing
  • Vehicle layout and microphone arrays tuned for AVAS and PEPS sound evaluations

Conclusion: VSAC Design Is the Gateway to the Future of EV Acoustics

The soundscape of electric vehicles requires a completely different testing philosophy.
High-frequency capability, refined omnidirectional source design, and advanced absorption materials are now at the core of effective VSAC solutions.
Sonora continues to lead this evolution.

Learn more about Modular Fully-Anechoic Chamber (MFAC)

Learn more about Modular Semi-Anechoic Chamber (MSAC)

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