Temporal time structures of formant damping and excitation
Gunnar Fant · The Journal of the Acoustical Society of America · 1979
The frequency and rate of decay of a formant oscillation is known to be influenced by the pitch synchronous variation in glottal impedance. Multiple excitation within the voice period adds to the variability. Furthermore, the residue of the glottal pulse adds substantially to a nonuniform pattern of zero crossings in the speech wave. Because of different degrees of dependency on glottal damping, formants exhibit vowel and mode specific contours of the decay of the envelope. Time domain calculations based on Laplace transforms bring out the relative role of various factors and focus on the voice pulse residue as a component equivalent to a formant. Changes of the relative balance between the vocal pulse residue and formant oscillation within a voice breath group are discussed. Experiments on the perception of nonuniform decay provide a basis for defining equivalent bandwidth.