Iterative metric-based waveguide optimisation

MacDonald L, Oclee-Brown J, Dodd M, Hargreaves J. Iterative metric-based waveguide optimisation. In: AES Convention 155. Audio Engineering Society; 2023. Paper 146. Available from: https://aes.org/publications/elibrary-page/?id=22300

@inproceedings{MacDonald2023_22300,
  author = {MacDonald, Lewis and Oclee-Brown, Jack and Dodd, Mark and Hargreaves, Jonathan},
  title = {{Iterative metric-based waveguide optimisation}},
  booktitle = {AES Convention 155},
  note = {Paper 146},
  year = {2023},
  month = oct,
  publisher = {Audio Engineering Society},
  url = {https://aes.org/publications/elibrary-page/?id=22300}
}

TY  - CPAPER
TI  - Iterative metric-based waveguide optimisation
AU  - MacDonald, Lewis
AU  - Oclee-Brown, Jack
AU  - Dodd, Mark
AU  - Hargreaves, Jonathan
T2  - AES Convention 155
M1  - Paper 146
PY  - 2023
DA  - 2023/10/06
UR  - https://aes.org/publications/elibrary-page/?id=22300
PB  - Audio Engineering Society
LA  - en
AB  - This paper explores an automated iterative optimization process aimed at enhancing the performance of acoustic waveguides that are thin in one dimension, by making them better at supporting single parameter (1P) wave propagation across a wide frequency range. The optimization process is driven by two performance metrics that are calculated from the solution of Laplace’s equation in the waveguide. These highlight regions of error in the relative pathlength (‘stretch’) and change in area (‘felt area’) continuously through the domain. Finite Element Analysis (FEA) is used to calculate these metrics on a test case. The error in the metrics is reduced using a fast iterative optimization loop which equalizes the relative pathlength and adjusts the area expansion of a thin domain by adding position-dependent corrugations and deformations, as is covered in GP Acoustics patent GB2588142 (Dodd & Oclee-Brown, 2021). The relationship between the waveguide metric errors and the acoustic wave coherence is investigated during each iteration for a simple test case. The metric-based optimization approach is then used to create a wide directivity line array horn and wave-shaper. FEA simulations of the Helmholtz equation are used to analyze the performance of the assembly, and the results are compared to a traditional wave shaper with a line array conical-diffraction horn and an exponential horn.
ER  -