Overcoming Challenges of Measuring Distortion Audibility in Vehicles

Temme S. Overcoming Challenges of Measuring Distortion Audibility in Vehicles. In: 2026 AES 6th International Automotive Audio Conference. Audio Engineering Society; 2026. Paper 2. Available from: https://aes.org/publications/elibrary-page/?id=23396

@inproceedings{Temme2026_23396,
  author = {Temme, Steve},
  title = {{Overcoming Challenges of Measuring Distortion Audibility in Vehicles}},
  booktitle = {2026 AES 6th International Automotive Audio Conference},
  note = {Paper 2},
  year = {2026},
  month = jul,
  publisher = {Audio Engineering Society},
  url = {https://aes.org/publications/elibrary-page/?id=23396}
}

TY  - CPAPER
TI  - Overcoming Challenges of Measuring Distortion Audibility in Vehicles
AU  - Temme, Steve
T2  - 2026 AES 6th International Automotive Audio Conference
M1  - Paper 2
PY  - 2026
DA  - 2026/07/29
UR  - https://aes.org/publications/elibrary-page/?id=23396
PB  - Audio Engineering Society
LA  - en
AB  - Standardized measurement of in-car audio systems remains an ongoing challenge, particularly regarding microphone configuration and placement, test signals, and correlation with perception. Current recommendations from the AES Technical Committee on Automotive Audio (TC-AA) advocate spatial averaging using multi-microphone arrays to improve repeatability. While this method reduces the influence of reflections and standing waves in the cars cabin to improve measurement consistency and repeatability, it limits frequency, phase, and amplitude resolution, which helps identify the root causes of the distortions and evaluate their perceptual impact. An alternative approach is to apply frequency-normalized distortion analysis, in which reflections or standing waves in the frequency response are also echoed in the distortion results, and greatly reduced by direct comparison of the two measurements. In this paper, we demonstrate that normalized distortion calculations provide clearer and more accurate THD measurement than conventional THD. We also show that THD measurements captured with a single microphone correlate well with those made with a 6-microphone array, indicating that this might be a viable lower-cost solution for end-of-line tests. Buzz, Squeak & Rattle (BSR) measurements, also known as Rub & Buzz or Impulsive Distortion measurements, are also challenging. The Crest Factor algorithm recommended by TC-AA adequately detects transient distortions but is susceptible to background noise and therefore requires a quiet environment for making measurements. Two other methods, enhanced perceptual Rub & Buzz and enhanced Loose Particles, offer improved repeatability in the presence of background noise, and the results are easier to correlate to audibility.
ER  -