Source-Filter Theory
Quick Definition
The acoustic model describing voice production as a sound source (vocal fold vibration) modified by a filter (vocal tract resonances).
Factual Definition
The theoretical framework established by Fant (1960) describing voice production as the convolution of a glottal source spectrum with the transfer function of the vocal tract. The source provides the harmonic series; the filter selectively amplifies harmonics near formant frequencies to create vowels and vocal timbre.