People are most familiar with countersurveillance from the movies and television, where the two main forms of these, human and electronic, are used quite liberally, though perhaps not accurately. Most of the human method is used; which involves using the environments to mask movement and sounds. On the big screen this is as simple as, 'loosing the tail'. Evading the surveiling body through crowds, transportation or hiding. At it's core this is countersurveillance, however the electronics means found on film are much more likely to be used in real-world security scenarios, than the running and hiding of spy thrillers.
Electronic countersurveillance includes the jamming of transmissions as well as the sweeping for and detection of surveillance devices, such as bugs, audio and video recorders and the like. Different gear has different effectiveness depending on the level of sophistication and the same is true of the counter devices. It is a constant one-upping in the industry between the devices and their countermeasures.
The use and counter-use of these types of devices has been traditionally a military and law enforcement strategy. A lot of what me know of these types of devices comes from ex law enforcement and military who turn to the private sector as private detectives, bodyguards or security consultants. As those industries became more popular and profitable countersurveillance devices began to become more widely available on a personal level. Because criminals have these sorts of tools at their disposable and have become more sophisticated in their techniques, many business and homeowners have sought to similarly up their game with available technology.
There are many devices that can be employed to enhance your security, some of which include the following.
Voice Changers: Sometimes the 'bad guys' are listening for information from a specific person, perhaps even triggering more attention when that target voice is heard on their listening devices. A voice changer can really throw off their game. If they are trained to pay close attention to a specific voice, they may not get the information they want when you use a voice changer. These can be used in combination with a cell phone as well, to really throw off the competition.
Wire Tap Detectors: There are many of these types of devices, inquire with a spy gear store for the best choice of equipment for you. These device check known frequency for bugs and use an indicator light to help you find the source of surveillance.
GPS Detectors: Similar to wire tap detectors, you can use GPS detectors to check your vehicle, clothes, accessories or bags for these little devices which seek to track your every movement and let others know where you are at all times.
White Noise Generators: Most often you will place these within crawl spaces or the corners of rooms. These generate white noise which will disrupt and highly degrade the sound quality of any attempted audio recording. More advanced models can be placed anywhere it a room and generate noise at frequencies designed to specifically degrade recorded audio within a given space.
These are just a few of the devices. Laser and UV detection, wireless detection and multi-use tools that care out several of these actions all at once are available based on budget and needs. If you have questions send inquiries to well-known countersurveillance equipment suppliers.