Abstract: Methods and apparatus for choreographing and synchronizing movement of individuals for an event are disclosed. In an embodiment, a method includes providing each individual of a group with a wireless audio playback unit, and transmitting body movement instruction signals to the audio playback units of each individual of the group. The audio playback units are configured to receive the signals and to play audio directions for each individual that correspond to choreographed and coordinated body movements to carry out the event.

Abstract: A system for controlling the bias of an amplifier samples a fraction of the amplified input signal, attenuates the sampled signal, detects the attenuated signal, compares the detected voltage with a reference voltage and supplies a logic level, receives this logic level and generates a control signal applied to the signal attenuator so that the detected voltage is substantially equal to the reference voltage, and generates the bias signal. The bias signal generator receives the control signal from the control signal generator. The bias of the amplifier is the lowest possible commensurate with amplification of the input signal without clipping.