Question

why are sound waves called mechanical waves​

Answer 1

Sound waves are mechanical waves because they need a material medium for propagation, like air or liquids like water, or metals like silver. ... The other type of waves, called electromagnetic waves (like light) do not need a material medium to travel, and can even go through vacuum.

Answer 2

Sound waves are mechanical waves because they need a material medium for propagation, like air or liquids like water, or metals like silver. That is the defining criterion for a mechanical wave, and the answer to your question.