  In this exceedingly short review article, we have provided some information
on acoustic topological insulator for pedagogical purpose. Since, intrinsically
acoustic systems do not have Kramers doublets due to spin-zero status,
artificially acoustic spin-half states could be engineered as reported in refs.
5-26 maintaining time reversal symmetry. The high point of this article is an
explanation of emergent Dirac physics in acoustic topological insulators.
