Which type of complex sound is a vowel classified as?

A vowel is classified as a periodic complex sound. This classification is based on how sound waves are generated and perceived. Periodic sounds are characterized by a waveform that repeats at regular intervals, which creates a consistent pitch that you can identify. In the case of vowels, the sound waves produced by the vocal cords create a regular pattern, resulting in a harmonic structure that embodies multiple frequencies, known as harmonics.

Vowel sounds are rich in resonant frequencies, or formants, which help distinguish one vowel from another but the fundamental nature of a vowel involves these periodic characteristics. This is contrasted with aperiodic sounds, which do not have a regular waveform and are often perceived as noise. Phonemic classifications relate to the linguistic aspects of sound rather than the acoustic properties, and while "formant" describes specific resonances related to vowel sounds, it does not define the overall classification of the sound itself as periodic.