The sound a given drum can possibly produce is completely determined by the spectral of the a differential operator, i.e. Laplacian, with Dirichlet condition. On the contrary, if we are capable of hearing all the sound or equivalently we know all the eigenvalues of Laplacian, then how much can we know about the drum? A more appealing way of saying that is can we hear the shape of a drum? I will discuss some known results of this question. This talk aims at general audience.