LightSpeed Technologies LES 400 Series is a Listening Enhancement System designed for sound-field classroom amplification. It improves speech recognition, classroom management, and academic achievement, while reducing teacher voice fatigue and throat illnesses. The system includes a receiver/amplifier, a belt pack transmitter and microphone, and an optional hand-held microphone. The receiver/amplifier has adjustable microphone and auxiliary volume controls, and a mixed audio output for connecting to assistive listening devices.