In my project I use electret mic + opamp to capture audio, which is later used for speech recognition on a remote site. This works well when operates in a silent environment, but not when there is some interference that comes from another direction (for instance, a conversation near by).
I wonder how hard it would be to perform some simple analog voice cancellation by adding another mic + opamp a few centimeters from the first one (the device's total size is a few centimeters), in order to filter out audio signal that comes from the side and only keep the audio signal that comes from a source perpendicular to the two mics.
I tried to search a little and found some info about beamforming. However, I'm looking for a solution which is simple and cheap, and doesn't require digital signal processing.