Effects of noise type and delivery method on voice production and task load during simulated teaching

Vocal responses to elevated background noise (Lombard effect) show promise for clinical voice assessment for occupational voice users, but implementation is limited by impractical loudspeaker setups in clinical environments. Additionally, the relationship between communication-related stress and voice use suggests that different noise types may impact vocal behavior differently. This study investigated how individuals adjust their vocal patterns in response to different types of background noise (pink noise versus babble noise) and noise delivery methods (loudspeakers versus open-air headphones). Participants simulated grade-school lectures under the four noise conditions calibrated at 75 dBA. Vocal responses were measured using sound pressure levels (SPL), self-perceived vocal effort through the Borg CR-100 scale, and subjective task difficulty was assessed using the NASA Task Load Index (NASA-TLX). Participants demonstrated equivalent changes in vocal loudness and perceived task difficulty regardless of noise delivery method, suggesting that open-air headphones can effectively replace traditional loudspeaker setups. Babble noise was consistently rated as more challenging than pink noise across both delivery methods. These findings validate the use of open-air headphones for Lombard effect studies in clinical environments and highlight the differential impact of noise types on communication stress. This research provides valuable insights for clinical voice assessment protocols.