What are some examples of surveillance listening devices?

Some surveillance listening devices are parabolic microphones, parabolic dishes and sound amplifiers. Audio bugs, body wires and spy phones are some other surveillance listening devices.

The parabolic microphone is a collapsible, 20-inch, six-panel dish utilized for long-range listening to a maximum of 300 yards. Its equalizer allows the user to adjust the microphone to specific sound frequencies. The parabolic dish is an extremely lightweight 12-inch dish used for medium-range listening. It is a directional microphone and amplifies sound to up to 40 decibels. It doesn't amplify high-decibel sounds thereby making it safe to use. The sound amplifier also amplifies sound but is meant mainly for personal use.