TV actors need to learn to use lav mics (Lavaliere microphones). A microphone array is any number of microphones operating in tandem. This involves the use of audio equipment such as microphones, recording devices, and loudspeakers. Transducers (i.e., microphones and loudspeakers) can also ring. Popper uses Shure microphones and Mesa Boogie amplifiers. Other accessories included speakers, microphones and control consoles. Some microphones such as condenser microphones require power. The devices tested incorporate multiple microphones, speakers and an auditory processor. This is similar to the phantom power technique commonly used for powering condenser microphones. The stereo effect is achieved through differences in sound pressure level between two microphones. Telescreens are devices that operate as televisions, security cameras, and microphones. They are typically used to amplify signals from analog sensors such as microphones and pickups. The equipment consisted of numerous speakers, turntables, and one or more microphones. This makes it useful for use with wireless microphones or other audio sources. An acoustic guitar can be amplified by using various types of pickups or microphones.