1. A speech recognition system comprising: a light element; a power control switch coupled between the light element and an AC power supply, the power control switch varying the power delivered to the light element; a controller coupled to the power control switch; a first auxiliary sensing device having an output coupled to the controller; a microphone; a speech recognizer coupled to the microphone for recognizing speech input signals and transmitting recognition results to the controller; and a speech synthesizer coupled to the controller for generating synthesized speech, wherein the controller varies the power to the light element in accordance with the recognition results received from the speech recognizer and the output of the auxiliary sensing device.