Are real non-sinusoidal sound waves, such as square sound waves, always composed of sinusoidal waves? I know that non-sinusoidal sound waves can be created with an infinite number of sinusoidal sound waves as described by Fourier series. Of course real non-sinusoidal sound waves cannot be composed of an infinite number of sinusoidal waves. Because they are only composed of a finite number of sinusoidal sound waves, you can see that they have been composed of sinusoidal waves by the imperfect and wavy appearance that they have. Do all non-sinusoidal sound waves exist in this way, or can they be created in forms other than an imperfect combination of sinusoidal waves?