Acoustic source localisation and tracking, Eric A. Lehmann

As a result of my research on array-based speaker tracking in reverberant environments, a particle filter using the concept of importance sampling was developed and implemented in real-time on a standard desktop computer, running in conjunction with a 16 microphone array. Below are a few examples of what this real-time acoustic source tracker can do. The audio signal in the movie corresponds to the data recorded with microphone nr. 2, close to the bottom right-hand corner of the display. The green dot displays the estimated location of the acoustic source, the red markers show the history of the source location estimates over the last few frames (estimated source trajectory).

The only information used by the algorithm to localise and track the acoustic source are the signals recorded by the 16 microphones located at known positions in the room. The dimensions of the enclosure are about 3.5m x 4.5m x 2.7m. Odd-numbered microphones are placed at a height of 1.9m, even-numbered at 1.3m. The reverberation time (T₆₀) measured in the room is 0.5s, which is quite substantial for this type of application.

Please be aware that these movies require the proper Xvid codec to be displayed correctly under Windows/Mac. Otherwise, the video stream might freeze from time to time, and the video and audio streams might get out of synchronisation. Open source software (mplayer, xine, vlc) don't seem to have a problem with it though! You can get this type of codecs from various places on the www. Get it for Windows and Mac e.g. here, or just Google it, e.g. like this!