A voice controlled medical system with improved speech recognition includes a microphone in an operating environment and a medical device. The voice controlled medical system further includes a controller in communication with the microphone and the medical device that operates the medical device by executing audio commands received by the microphone. The voice controlled medical system further includes a calibration signal indicative of distortion in the operating environment which is generated by comparing an audio signal played in the operating environment with a sound signal received by the microphone. The controller uses the calibration signal to interpret audio commands received by the microphone.