This book is aimed for students and researchers alike who want to understand the basics of thermoviscous acoustics and who would like to uncover the untold mathematical formulations that are either overlooked or taken for granted. The book starts from the most fundamental and rudimentary treatment and presents and alternate way to tackle the problem of thermal gradients and particle tangential velocities due respectively to thermal conductivity and viscosity of the medium. Navier Stokes equations are solved in 3D using modified differential operators for isotropic plates. Sound propagation with thermoviscous effects is not only studied in air but the formulation is generalized to cater for any fluid e.g. water. Sound radiation in infinite space as well as transmission through double wall panels is also investigated. The book ends with the idea of a novel single equation for predicting the damping behavior of thin sandwich panels with thermoviscous fluid layer. Experimental validation is also presented.