Personal voice amplification systems are used by many teachers and presenters who require additional reinforcement to communicate in a normal voice ... whether to extend their effective reach (indoors or outdoors), or in noisy environments. The systems are all powered by batteries (usually rechargeable) and are conveniently warn or carried.
For more active situations, such as music, dance, drama, PE and outdoor activities, it is recommended that you choose a system with a hands free headset microphone.