Through an understanding of the spectral content of sound, linguists have discovered the structural role of vowels and consonants in creating the sound shape of language. Acoustic phonetics reveals the role of sound colour, or timbre in creating the underlying sound structures.

The voice is a complex sound consisting of a fundamental frequency and up to twenty harmonics. Harmonics are the result of sound waves set in motion, all vibrating at different speeds, or frequencies.

Spectral analysis of vocal sounds provides an acoustic mapping of the underlying sound structures of linguistic signs and symbols. Each vowel represents a characteristic spectrum. The phonetic quality of vowels is determined by regions of intense resonance at specific frequencies known as formants. Formants are created by resonating chambers within the vocal tract, head, and chest, which act as multi-resonance filters 2 , giving more acoustic energy to specific frequencies. Consonants are the result of rapid changes in resonance in the vocal tract. They give vowels form and place in the timbral stream, and have a high noise content, similar to the attack characteristics of percussion instruments. The word phoneme is from the Greek phonema, meaning sound. Phonemes are the smallest segments of sound that can be separated by their contrast within words. There are approximately twenty to sixty phonemes in any given language.