1. A system comprising: a microphone array having microphones that are responsive to sounds generated from within an environment to produce input microphone signals; a depth sensor that is configured to capture a depth image of at least a portion of the environment; and operating logic configured to perform acts comprising: analyzing one or more of the input microphone signals to detect a sound that has been produced from a source position; analyzing the one or more of the input microphone signals to determine differences in arrival times of the sound at the microphones of the microphone array; analyzing the differences in arrival times to determine a first estimate of the source position of the sound, the first estimate of the source position of the sound including a first confidence level based on a signal-to-noise ratio associated with the one or more of the input microphone signals; analyzing at least a portion of the depth image that encompasses the source position to detect a human body part in the depth image; determining a position of the human body part based at least in part on the depth image, the position of the human body part being associated with a second confidence level based at least in part on an accuracy of the position; and determining a second estimate of the source position based at least in part on a weighted average of the position of the human body part and the first estimate of the source position of the sound, the weighted average based at least in part on the first confidence level and the second confidence level.