One last type of microphone that falls outside convention - the boundary microphone. Originally manufactured by Crown under the trade name "PZM" (pressure zone microphone), now everybody makes one, including Radio Shack. The boundary mic is unconventional in that it lays on a table, floor or wall and effectively uses the entire surface for pickup. The larger the surface, the better the sound. By positioning the microphone element a fraction of an inch above the surface, the boundary mic eliminates phase cancellation and other strange things that happen to regular microphones. Boundary microphones excel at picking up large groups of people, background ambience and crowd noises (applause, laughter, etc.). On the other hand, they also excel at picking up air conditioning rumble, creaking doors and bystanders. While you can't use them in every situation, they are handy for corporate board meetings and video depositions. Just lay one or two microphones on the conference table and start recording. Just don't allow anyone to lay books or papers on your mics! You must experience this to believe it.