en.wikipedia.org/wiki/Acoustic_metric

In mathematical physics, a metric describes the arrangement of relative distances within a surface or volume, usually measured by signals passing through the ...

www.mathpages.com/home/kmath660/kmath660.htm

Therefore, for purposes of describing and analyzing the behavior of acoustic
disturbances in a medium, it is often convenient to use the **acoustic metric**
defined ...

www.researchgate.net/post/Should_general_relativity_use_an_acoustic_metric_to_make_it_more_compatible_with_QM

Einstein's 1916 general theory of relativity is now nearly one hundred years old. Einstein originally designed the 1916 theory to reduce to the physics of...

arxiv.org/abs/1508.00732

Aug 4, 2015 **...** ... of a planar black hole in asymptotic Anti-de Sitter space can, on a slice of
dimension 3+1, be reproduced as a relativistic **acoustic metric**.

www.sciencedirect.com/science/article/pii/S0370269315008746

Jan 10, 2016 **...** This is unfortunate because the near-horizon region is the most interesting part,
so we will here derive a relativistic **acoustic metric** and recover ...