Background: Vocal effort is a physiological entity that accounts for variation in voice production as loading increases, measured as sound pressure level (SPL). A number of studies have investigated vocal effort and load, but few have considered the role of acoustic clarity (C50), the early to late arriving sound ratio. Method: 20 subjects performed vocal tasks in various room acoustic conditions. Tasks were performed in three styles: soft style, comfortable conversational style, and loud classroom style. C50 in the position of the talker was changed by means of two reflective panels. Two noise levels were used: background noise, and artificial child babble noise. After each task, the subject answered questions addressing their perception of vocal comfort, control and fatigue. SPL and Fundamental Frequency (F0) were measured. Results: When panels were present, talkers perceived the room as being more comfortable to speak in. In particular, in the babble condition and in loud speech, comfort and control tended to increase. Vocal effort (SPL) tended to decrease when panels were present. An assessment of F0 is also reported. The results indicate that even while keeping reverberation time constant, reflective surfaces may be optimized to increase voice comfort and reduce vocal effort.