Speaker
Description
Speakers continuously adapt their voice to the acoustic environment, and prolonged speaking under adverse conditions may increase vocal load and contribute to voice problems. Classrooms constitute acoustically demanding environments, where both background noise and room acoustics influence vocal behavior through mechanisms such as the Lombard effect and altered auditory feedback. While these factors have been studied separately, their combined influence, and potential differences between speakers with and without voice problems, remain insufficiently understood.This study investigated the effects of room acoustics and background noise on vocal behavior, perceived vocal effort, and voice quality in a classroom-like environment. Nine female speakers, with and without self-reported voice problems, performed speaking tasks under four acoustic conditions and three noise levels (≈28, 65, and 75 dBA). The acoustic conditions differed in reverberation time (T20), clarity (C50), sound strength (G), voice support ($ST_V$), and mouth-to-ear decay time (DT40). Vocal sound pressure level (SPL), fundamental frequency (f0), perceptual voice quality, and self-assessments were analyzed using linear mixed-effects models.Background noise was the dominant factor, with increasing noise leading to higher SPL and $f_0$, increased dysphonia, and reduced speaker comfort. Speakers with voice problems produced lower SPL but showed reduced comfort and altered voice quality. Room acoustics showed limited main effects but moderated noise-induced vocal changes. Improved acoustic conditions were associated with increased comfort and audibility, although these effects diminished at higher noise levels.The findings indicate that background noise is the primary driver of vocal adaptation, while room acoustics exert more subtle, interaction-dependent effects. Differences between speaker groups suggest distinct vocal strategies in acoustically challenging environments.