What are microphone arrays?
Microphone arrays consist of multiple microphones functioning as a single directional input device: essentially, an acoustic antenna. Using sound propagation principles, the principal sound sources in an environment can be spatially located and distinguished from each other. Distinguishing sounds based on the spatial location of their source is achieved by filtering and combining the individual microphone signals. The location of the principal sounds sources may be determined dynamically by analysing peaks in the correlation function between different microphone channels.
Why research microphone array processing?
With the increased maturity in speech and speaker processing technologies, and the prevalence of telecommunications, there is a need for effective speech acquisition devices. As an acquisition device for speech, microphone arrays have a distinct advantage as they place few constraints on the user, freeing them from the need to ‘wear’ a microphone (as in lapel, headset, or mobile devices) or be near to and speaking towards the microphone (as in webcams and lecturn microphones, for example). Unfortunately, arrays also some disadvantages compared to individual microphone, including increased hardware and processing requirements due to the multiple channels, and acoustic losses due to the distance from the speaker. Research into microphone array processing is thus required to minimise these issues, enabling the advantages of microphone arrays to be exploited in practical systems.
Resources for microphone array research
For an overview of fundamental microphone array principles, here is a tutorial on Microphone Array Processing.
I have been involved in recording a number of databases suitable for research of microphone array processing methods. The databases generally include recordings from circular microphone arrays as well as close-talking microphones (either lapels, headsets or both). See the sub-page on Research Data for an overview of these, along with information on availability and reference publications.
I have also written a summary of some of the microphone array Research Directions I’ve been involved with over the years.
Finally, if you are interested in commercial microphone array software or devices, I have formed a start-up company called dev/audio that is currently developing its first range of products.