Sound waves are longitudinal in nature. When we speak, sound waves travel through the air medium and reach the audience. An example of a sound wave in the longitudinal direction of propagation is a tuning fork. In the case of acoustic waves, the amplitude of the wave is always the difference between the maximum pressure caused by the wave and the undisturbed air pressure. The propagation speed of sound depends on the type and composition of the medium and the temperature at which it propagates.