Deconstructing Timbre into 5 Physiological Parameters: Vocal Mode, Amount of Metal, Degree of Density, Size of Larynx, and Sound Coloring

Timbre has been related to adjustment at the source as well as adjustments in resonance, including laryngeal height and hypopharynx area and volume. However, it is often presented in vocal pedagogy as solely related to resonance. Very little data is available on the laryngeal adjustments at both source and resonance involved in achieving various timbres across a variety of phonation types. To systematically assess the independent laryngeal adjustments at the source and independent laryngeal adjustments in the vocal tract necessary to obtain the lightest and darkest timbral extremes for four different phonation types. Twenty-one professional singers produced a sustained vowel “EH” as in “stay” in each of the four phonation types (“UH” as in “hungry” for one type), varying the sound coloring to the lightest and darkest of their ability without altering pitch, vowel, or loudness. The singers were observed using laryngostroboscopy and electroglottography. A systematic assessment protocol covering 31 laryngeal gestures was developed based on previous research for objectively classifying changes in laryngeal setups. Darkening and lightening the sound color involved altering the size of the vocal tract space related to lowering/raising the larynx, widening/closing the piriform sinuses, increasing/decreasing the distance between stylopharyngeus and palatopharyngeus, increasing/decreasing anterior-posterior narrowing (and the resulting view of the vocal folds), medialising/retracting ventricular folds, and altering supraglottic funnel depth. The phonation types did not show equal ability to be colored. Female singers exhibited less coloring variation compared to the males. Classical singing exhibited both lightening and darkening colouring features. The singers were able to produce a variety of different timbral expressions within each of the investigated four phonation types by coloring the sustained note darker or lighter using laryngeal adjustments. Timbre is deconstructed as a perceptual artefact defined by (1) the choice of vocal mode, (2) the amount of metallic character, (3) the degree of density in the note, (4) the chosen sound color, and (5) the natural size of the larynx and vocal tract.