After providing an overview of the technology and equipment used in law enforcement communications, noise and its effect on communications are discussed. "Noise" is defined as "sound that disrupts messages or makes no sense to the circumstances at hand when heard." An examination of the various forms and causes of noise addresses "ambient" noise, i.e., the type of noise normally found in a particular environment. Police training in communications should focus on the types of environments in which officers are likely to find themselves and types of noise likely to be associated with these environments, as well as methods that can reduce the negative impacts of such noise on police communications. Officers should be instructed to keep their distance from noise sources and keep car windows closed when transmitting communications from within the car. If headsets are available and the environment is safe, then they should be used. Noise-cancelling microphones can be used in environments that have excessive noise. Law enforcement supervisors should review their communications needs and determine the range of environments that officers may confront. Equipment should be tested in order to enable personnel to hear what happens to communications in various environments and how communications impaired by noise can be improved.