Trained Belting and Untrained Shouting – How Do They Differ?
Objective: This exploratory study investigated differences between belting (‘yell-like’ singing) by trained singers and shouting by untrained participants. Special interest was in parameters estimating vocal efficiency and economy.
Methods: Ten trained professional singers with expertise in belting and 10 vocally untrained individuals (males and females) produced moderately loud and very loud syllable repetitions of /pe/ at three pitches (males: C#4, D#4, F4 and females: F4, G4, A4). Oral air pressure, flow, electroglottographic (EGG), and acoustic signals were recorded. Thirteen parameters were calculated, including subglottal pressure (Psub), average air flow (Q), estimate of glottal resistance (GR), contact quotient (CQ), alpha ratio, level difference between the first and second harmonic (H1-H2), spectral centre of gravity (CG), and sound pressure level (SPL). Twelve parameters estimating vocal efficiency and economy were calculated, including efficiency (VE), SPL/Psub, SPL/CQ, and quasi output cost ratio (QOCR). Group differences between belters and shouters were explored separately for the males and females.
Results: Eighteen parameters in males and nine in females differed significantly (p < 0.05) between the groups. VE in dB (re 1 W) was higher in belting in both sexes (p < 0.01). Male belters also showed lower Q, subglottal power (Psub * Q), H1-H2, SPL/Psub, and QOCR, as well as higher GR, CQ, and SPL/Q, than shouters. Female belters demonstrated lower Psub and CQ, and higher CG, SPL/Psub, QOCR, and SPL/CQ than shouters.
Conclusions: Trained belters demonstrated greater efficiency, producing similar acoustic output to the shouters, but with less subglottal power. This result may reflect differences in vocal skill. Somewhat counterintuitively, some economy estimates were lower in male belters than in shouters. This was due to the trained males’ significantly higher Psub and CQ. It is questionable whether the economy estimates approximating vocal fold impact stress based on CQ and Psub perform well in high-intensity phonation.