DIY

CIRCUITS

THE STEALTH MIC

Disguise an inexpensive binaural microphone as ordinary earbuds. By Bill Byrne

A binaural recording system re-creates the way a person actually hears by placing 2 microphones at a distance of about 7" (roughly the distance between your ears), usually mounted on a dummy head or worn on the human recorder’s head. When played back on headphones, the binaural stereo effect is preserved and is often quite remarkable in its realism.

Photograph by Sam Murphy

With some easy modifications, a pair of headphones can be turned into a binaural microphone with readily available materials and cheap parts. Better yet, I’ll show you how to make your own binaural mic, disguised as earbuds.

In today’s iPod-saturated urban environment, no one ever notices someone wearing headphones. This makes earbuds an ideal prop for covering a hidden mic that’s plugged into a recording device, for various stealthy endeavors.

MATERIALS

Microphone condenser elements ( 2)

RadioShack part #270-090 Solid-core wrap wire, 30 gauge in 2 colors Soldering iron and solder

1" heat-shrink tubing

Lighter

1" stereo plug

Earbud cushions

1. Wire the binaural mic elements. Normally I don’t use wrap wire because it’s so thin it can be frustrating to deal with, but in this case, for earbuds, we really need the wires to be thin and lightweight.

Cut two 3' lengths of wrap wire in each of 2 colors. Solder these to the first microphone element’s 2 contacts (Figure A, next page). Slide a couple inches

Make: 161