What is sound? … Sound is a mechanical wave produced by vibrations that travel through a medium, such as air, water, or a solid. waves What is a wave? … A wave is a disturbance that transfers energy from one location to another. harmonic waves For a sinusoidal sound wave traveling in the positive (x)-direction: p(x,t)=pmcos⁡(ωt−kx+ϕ)p(x,t)=p_m\cos(\omega t-kx+\phi)