Speakers adjust their vocal production when communicating in different room acoustics, when instructed to speak at different volumes and when experiencing vocal fatigue. The present paper reports on the effects of speech style, reverberation time, and external auditory feedback on time dose and fundamental frequency. Ten male and ten female subjects were recorded while reading a text in normal and loud styles, in three rooms—anechoic, semi-reverberant, and reverberant—and with and without acrylic glass panels at 0.5 m from the mouth, which increased external auditory feedback. Longer time doses were accumulated in more reverberant rooms, especially when loud voice was used. Higher fundamental frequency was measured in less reverberant rooms. Subjects increased their fundamental frequency in the loud speech style versus the normal style, but this effect was weaker when the level of external auditory feedback was high. A larger fundamental frequency range was detected for females than males and for the loud style than the normal style. These results contribute to understanding how the effect of room acoustics on speech changes as a function of speaking time.