There are many different kinds of listening devices on the market right now. The can be as big as a 20-inch parabolic dish, as small as a wristwatch, or even as small as a matchstick lapel microphone.
Listening devices can also be used for a lot of other things besides spying. Listening devices like the Bionic Ear have been used to amplify animal sounds for personal safety, record bird calls for nature photography, and were even used during Desert Storm. You can even make great recordings as gifts with your recorder and listening devices.
A camera or DVR system can be added to with some listening devices. Other things can pick up sounds accurately from as far away as 300 yards. Listening devices can boost sound by up to 30 decibels and record with sound as good as in a concert hall. There are also listening devices called "concrete microphones" or "electro-acoustic receivers" that can pick up tiny vibrations like those made by a bomb. Professional plumbers can use these devices to find leaky pipes in the foundations of homes. Of course, they can also be used to find the source of a voice leak and where it is coming from in a room. They can find vibrations in almost any solid surface, including steel, glass, concrete, and wood.
One of the best ways to use listening devices is to help people who have trouble hearing hear better. These listening devices can pick up sounds from up to 100 yards away, and they are small enough to fit in a woman's purse or a man's shirt pocket. One of the best things about these listening devices is that they can weigh as little as three ounces and reduce feedback and scratchiness.
