Sound can be described as a pressure disturbance that travels through the constituent particles of a medium: as one particle of the medium is perturbed by the pressure, it exerts a force on an adjacent particle, thus perturbing that particle in turn. The speed of sound reflects the speed at which the disturbance is passed from particle to particle, or the distance it travels in time. This form of pressure disturbance is propagated through the medium exclusively as a longitudinal wave in the case of gases and liquids, i.e., a type of wave in which the displacement of the medium is parallel to the propagation of the wave. In this case, the speed of sound refers to the distance a compression or a rarefaction point travels per unit time. In solids however, sound may propagate as a transverse wave, i.e., a type...