There are all types of listening devices available on the market today. The can be as large as a twenty inch parabolic dish, as small as a wristwatch, or even as small as a matchstick lapel microphone.

Listening devices have many more uses than just surveillance work, too. Listening devices such as the Bionic Ear have been used for magnifying animal sounds for personal safety, recording bird calls for nature photography, and were even used during Desert Storm. You can even use listening devices with your recorder to make fantastic recordings as gifts.

Some listening devices can be added onto a camera or DVR system. Other devices can accurately pick up sound from as far as three hundred yards. Listening devices can increase sound up to thirty decibels and record with concert-hall quality sound. There are other listening devices called concrete microphones or electro-acoustic receivers that can pick up minute vibrations like those given off by a bomb, and professional plumbers can even use them to locate leaky pipes in the foundation of homes. Naturally, they can also be used to identify voice leakage and their sources in a room, as well. They can detect vibrations in virtually any solid surface whether it's steel, glass, concrete or wood.

One of the best uses for listening devices is to amplify sound for the hearing impaired. These listening devices can pick up sound from as far away as one hundred yards, and they are small enough to fit into a woman's purse or a man's shirt pocket. One of the best features about these listening devices is that they minimize feedback and scratchiness and weigh as little as three ounces.