A triangular wave also has only odd numbered frequency components. Trying to represent actual sounds as sums of true sine waves, which persist from an infinite past into an infinite future, is a mathematical artifice. Consider the nearly periodic sounds produced by musical instruments. When the sound is repeated the waveforms won't be exactly the same. The power of the sound in any narrow range of frequencies will be about the same, but the amplitudes and phases of the individual frequency components won't be identical.
Most sound generators produce recurrent waves which are generally similar to each other.
These waves are propagated at a definite velocity. This velocity depends on the medium of propagation. One cycle of a sound wave in air, consists of one compression of the air together with the subsequent rarefaction that occurs. The equilibrium state of the air molecules is the state in which they were before the compression under observation occurred. In doing so they acquire momentum and thus become compressed again and so on.