How to Sweep Room for Electronic Listening Devices

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Is someone listening in on your conversations?

Covert listening devices, or "bugs," are used not only by the government, but also by businesses and individuals who wish to eavesdrop or to spy on others. Although some of these devices are so technologically advanced that they are virtually undetectable, most bugs can be discovered with relative ease because of their reliance on power sources and radio/cell phone signals. To determine if a listening device has been installed in your home, office, or vehicle, you will need to examine all power sources and scan for radio/cell phone frequencies in the area.

Checking Power Sources

Step 1

Switch plate

Remove all the outlet plates and switch plates in the room you are searching using a screwdriver. Once you remove a plate, you should see a rectangular hole containing a mass of wires in the wall behind it. These holes are prime locations for hiding listening devices because they provide easy access to a power source: the wires.

Step 2

Outlet wiring

Shine your flashlight into each of the holes in the wall. You should see nothing but wiring inside. If you notice anything that looks suspicious or out of place, do not touch it. Contact law enforcement officers and tell them what you have found.

Step 3

Inspect any other accessible power sources that may be in the room--for example, fuse boxes and light fixtures--in the same manner. Again, if you find anything, call the police.

Step 4

Check attic and crawl spaces as well. In these areas there is usually a lot of exposed wiring, an easily accessible power source.

Calibrating the RF Detector

Step 1

Turn on your RF (bug) detector, turning the dial all the way up and set it on a flat surface. It should start beeping rapidly.

Step 2

Turn the dial on the RF detector back down until the beeping completely stops.

Step 3

Make a call from one of your cell phones to the other while standing right next to the RF detector. It should start beeping rapidly again.

Step 4

Move about 10 to 12 feet away from the RF detector while keeping the cell phone connection open. The detector should continue beeping, but more slowly, at a rate of approximately 160 beats per minute. If it is beeping more slowly than 120 beats per minute (about two per second), turn the dial up slightly to increase its sensitivity. If it is beating more quickly than 160 beats per minute, turn the dial slightly down.

Doing the Bug Sweep

Step 1

Move the RF detector slowly over the surfaces of all electronic devices in the room, keeping it about two feet away from each device. If it starts to beep, ensure that the device you are scanning is turned off and scan it again. If the RF detector continues to beep rapidly, you may have found a bug.

Step 2

Repeat this process with all the nonelectrical objects in the room--desks, chairs, file cabinets, etc.--and finally with the walls. A single beep from the RF detector probably does not indicate that you've found a bug; listen instead for rapid, continuous beeping, which would indicate a radio signal transmission.

Step 3

Contact law enforcement if you believe you have found something.

Things You'll Need

  • Screwdriver

  • Flashlight

  • 2 cell phones

  • Radio frequency (RF) detector (also known as a bug detector)


Turn off all major electronics in the room--such as the television, DVD player, and stereo--before performing the bug sweep. Be sure the RF detector is calibrated as described in Step 2. If you put it on too sensitive a setting, it may pick up on even electromagnetic waves coming from appliances and outlets. If you think you know where a bug is located but do not get a signal, set the RF detector down close to where you think the bug is hidden and wait five to 10 minutes. Many transmitting devices emit a signal every five minutes by default, and when the signal is sent out, the RF detector should start beeping rapidly.


If you believe that you have found a bug or listening device, do not touch it. Call local law enforcement and ask them to come check it out. If you move the device, it will no longer be valid as evidence. The methods described in this article are not effective with all listening devices. If you find nothing but continue to receive evidence that others are privy to your conversations, contact a professional investigator or law enforcement.

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