We all know what listening devices are, but have you ever wondered how they work? In this article, we’ll answer the following questions about eavesdropping detection devices:

• How far away can listening devices hear a conversation?
• Do listening devices make noise?
• Can listening devices hear through walls?
• How do listening devices work?
• How do you detect listening devices?

People use these kinds of devices to hear conversations from a distance so that the people who are talking do not know someone else is listening to their private communications.

The police will often use listening devices to spy on certain suspects who they have reason to believe are involved in criminal activity. Companies use listening devices to spy on competing businesses and overhear confidential information. Because of this, it is extremely important for corporate offices to sweep the room where meetings are being held for listening devices and hidden cameras. Parents also use these products when they want to ensure their children are being cared for properly by a babysitter or a nanny. They can buy a listening device that records audio to hide in the home and listen to the recording later on.

How Far Away Can Listening Devices Hear a Conversation?

Some of these devices can allow someone to hear a conversation from 100 yards away, while others have a range of 300 yards, depending on what type of listening device is being used.

Here are a few different listening devices that you can find:

• Cell phones – look like cell phones but do not function as a phone — performs as a wireless transmitter and allows someone to spy on others, inconspicuously
• Long-distance sound receivers – parabolic/laser microphone devices
• Tiny listening devices that can hear through walls – looks like a mini stethoscope microphone – plugs into a radio receiver/headset
• Bionic ears – allows someone to hear a conversation within a 100-yard range – Amplifier systems are available, which amplify the audio
• Digital voice recorders – digital pen recording devices, phone recorders powered by USB, and wearable voice recording devices

Do Listening Devices Make Noise?

Technically, they do not make noise that the human ear can pick up, which can make it hard to detect a listening device in your home or office. There are, however, slight noises someone can try to hear if they believe another person is eavesdropping on his or her conversations on their cell phone.

If there is an audio bug in a phone, instead of using the phone’s speaker to listen while talking on the phone, use headphones. Why? If the phone has a listening device in it, you will hear a slight static noise like radio stations do when they are not tuned in properly.

Otherwise, most listening devices cannot be detected by listening for unusual sounds or static. They are designed to be discreet so that no one knows someone else is tuning in to their private conversations. If you do suspect your home or office has been bugged, the best way to confirm the presence of a listening device is to bring in a professional who has the equipment needed to detect what the human ear can’t.

Can Listening Devices Hear Through Walls?

Yes, listening devices have a high-end frequency range that can hear conversations through the walls of an office building or home, whether they are made from brick, concrete, sheetrock or other materials.  An audio surveillance device can even allow someone to hear whispering in the adjacent room as long as the microphone is sensitive enough. To keep your corporation’s confidential information safe, consider building a Sensitive Compartmented Information Facility (SCIF) room.

How Do Listening Devices Work?

Listening devices themselves are very tiny and have even tinier microphones inside them as well. The devices are so small that they are usually overlooked by most people and can be hidden in a variety of places. Some of these products are designed to look like everyday items, such as pens, which makes these devices discreet and easy to plant in any meeting room or household.

How Do You Detect Listening Devices?

Detecting listening devices is tricky, especially as technology continues to advance and these devices shrink in size, making them harder to spot with the human eye. They can also be designed to look like everyday items, such as pens & cell phones, so people would not consider the listening devices suspicious or might not know they are in their office, car, or elsewhere.

Methods for detecting listening devices

Here are a few methods for detecting listening devices:

• You might hear a slight buzzing sound or a small clicking sound if a recording gadget is hidden
• Look inside of smoke alarms and other similar hiding spots
• Look for an odd, tiny wire that is not attached to anything else
• Inspect light fixtures
• Look under the hood of your car (likely near the battery)

Tools for detecting listening devices on today’s market:

• RF detectors – can be used to scan for radio frequencies utilized to transmit a microphone or a hidden camera
• A digital camera – used to look for infrared lights, which are utilized by spy cameras
• Some devices connect to the Internet – if the Wi-Fi signal is strong, the device is probably close by

The best method for detecting a listening device though is hiring a security company that offers professional TSCM services. This includes sweeping for bugs with high-tech equipment that can find even the smallest of listening devices. Contact Silent Guardian Security for bug-sweeping services in the New York City area.

LEARN MORE ABOUT OUR TSCM & BUG-SWEEPING SERVICES