The speed of sound in materials of various states of matter differs a lot.
But does it have fundamental limits?
Is there a maximal possible speed of sound?
Is there a minimal possible speed of sound?
Is the speed of sound in a material a multidimensional function of many uncorrelated dimesions of material properties, and current state states, such that the function ends up as a vast unknown n-dimensional surface where we not even know in which direction to look for a maximum, and are already happy to find a local maximum at all?
Obviously, the speed of light in vacuum is a upper limit for the speed of sound in general. But that does not imply that, for a given Material, the material specific speed of light is an upper limit for the speed of sound in the material.
Of course, in the set of speeds of sound in all materials where it can be measured, there is a maximum and a minimum.
But there are some materials where we can not currently measure the speed of sound, say short lived isotopes available in small numbers of atoms, neutron stars, and other things your university can not order for the laboratory.
From a theoretical perspective, maybe one yould reason about speed of sound independent of existing or potentially existing materials?