Formation of the actor's/speaker's formant: a study applying spectrum analysis and computer modeling

A strong peak between 3 and 4 kHz in the long-term average spectrum (LTAS) of speech has been found to be one correlate of a good male speaking voice, for example, among actors. The actor's or speaker's formant (resembling the singer's formant) can be established by certain vocal training. This study investigates the origin of the speaker's formant.

The immediate effects of a vocal exercise series on speaking voice were studied in a Finnish male actor, who is an experienced teacher of the exercises. They consist of nasal vowel syllable strings and words containing nasals. Before and after a 30-minute exercising, the subject (1) read aloud at three loudness levels and (2) phonated the Finnish vowels at habitual level.

Formant frequencies were estimated from spectra of the vowel samples. LTAS was made and equivalent sound level (L(eq)) was measured for the text samples. Formant frequencies were used as the input for a one-dimensional (1D) mathematical model.

After the exercise, the peak at 3.5 kHz in the LTAS of the reading samples was stronger, although L(eq) was the same as before, suggesting a level-independent resonance change. Reading samples after exercising were evaluated to sound better in voice quality than before exercising. The strong peak at 3.5 kHz was present in all vowels, and it was mainly formed by clustering of F₄ and F₅.

A 1D model-based optimization suggested that this kind of a formant cluster could be best established by simultaneously narrowing the epilaryngeal tube, widening the pharynx and narrowing the front of the oral cavity.