A microphone with two diaphragms. The second diaphragm may be electronically combined with the first to produce more than one polar pattern. In another type of dual diaphragm microphone, the two diaphragms are for high and low frequencies.
"I just want to tell you how pleased I am about the work you did for me recently. You took an old 3 inch reel with the voice of my mother-in-law who has been deceased thirty-three years and converted it to a CD. That old tape was found in our basement, stored there for twenty years. I asked you to convert it in time for Christmas, which you did. ..."