Background: Voice production involves balancing acoustic quality with physiological effort. While this relationship is widely assumed, empirical evidence remains limited. Vocal fatigue, a common complaint among professional voice users, may significantly impact this relationship. This study hypothesized that maintaining voice quality requires increased vocal effort, suggesting the existence of a quality-effort economy in voice production.

Methods: Thirty-nine participants completed speech tasks under two conditions: "Use your best voice" and "Use lowest effort". Each condition was tested before and after a 30-minute vocal loading task involving map descriptions over 75dB background noise. Voice quality was measured using Smoothed Cepstral Peak Prominence (CPPS), while self-reported vocal effort was assessed using Vocal Effort Rating (VER). Analysis examined changes between trials and correlations between CPPS and VER.

Results: In the good voice condition, changes in CPPS and VER showed a positive correlation (r = 0.414, p 0.10), suggesting participants prioritized effort conservation over voice quality. Between-condition comparisons revealed significant differences in CPPS changes (t = 2.075, p < 0.05) and a trend toward significance in VER changes (t = 1.633, p < 0.10).

Conclusions: This study provides evidence for a voice quality-effort economy, particularly under conditions of vocal fatigue induced by loud background noise. The relationship is demonstrated by the correlation between voice quality and effort in the good voice condition and their decoupling in the low effort condition.