Direction of sound using microphone array I want to estimate the direction of arrival of sound (angle in a 2d plane) using a microphone array. I'm hoping to follow a time-delay based method using a 4 mic array. The method requires me to find the time delay of the signal upon arriving at the different microphones. For example, in the 4 mic array, I'm required to find the time delay of the signal between mics 1 and 2, 1 and 3, and 1 and 4 and so on for all other pairs. It would be very convenient if I could have a 4 mic array that could simply be plugged into my laptop and I guess an NI Labview algorithm would take care of the rest. And some one somewhere suggested that the microphone array can be created by using 4 usb (mini) mic and connecting them to a USB hub. First of all, can this be done? Secondly, since its a USB mic, the signal will already be digitized right? Any suggestions regarding how to extract information about time from this? I do not have any prior experience with signal/sound processing.
If you connect four discrete USB microphones a challenge will be to synchronize them. Even when you start them simultaneously (from a programming point of view) you cannot be sure that they all start the audio acquisition at exactly the same time so there will be an inherent unknown time delay between the microphones. This can be solved by having a reference signal coming from a known direction. Then, by comparing the expected delays with the actual delays, synchronization can be achieved. With your setup I would expect the synchronization delays to be slightly different every time the system is started so that calibration needs to be done every time.