A microphone is an acoustic-to-electric sensor that converts sound into an electric signal. In film, all microphones are used during production picking up the sound of the desired character, ambience, sound effect, and other recorded sound. There are two types of sound recording within film, one being single system and the other being double. Single system sound recording consists of both visuals and sound being recorded from the same camera, while double system sound recordings, which is the professional norm, requires recording the audio on a separate machine from the camera and is synced to the video during post-production.
Wireless Body Microphones: Also referred to as a lavalier mic, is a small microphone that is hidden on a characters costume or mobile prop to capture close perspective sound of an individual’s voice. The microphone will also pick up other voices and sounds from within the surrounding area of range. However, being a wireless mic it requires an independent power source, which consists of a battery pack that also must be concealed. While the advantages of this microphone are its great caption of a single characters voice, the disadvantages are that it is vulnerable to radio wave interference, improper grounding within the production location, and friction noise from the actors clothes.
Boom Microphone: The Boom mic is very popular in television and film production, as they are the number one choice for most professional film sound production situations. The standard for the Boom mic is the shotgun microphone, which is a very powerful condenser mic with a focused and far ranging pickup, often used with widescreen and hard casing, while being mounted on a boom pole. The Boom can move freely without disturbing the sound its recording, and have the advantage of freeing up characters from having to worry about microphones. However, there are certain precautions which must be undertaken while using them, such as making sure the distance between the mic and the subject is controlled and consistent, preventing fluctuations in audio levels. Furthermore, many models are wired, requiring large power supplies and a skilled boom operator is needed to keep the mic out of shots, and avoid boom shadows.
Plant Microphone: The Plant microphone is set in a fixed place and is used to cover a subject when it is impractical to use a Boom mic. The actual placement of the plant mic is important because they are only effective if dialogue is directed within their pickup range. Furthermore, the mic must also be properly hidden and planted within the scene, which is where its name is derived from. The mics can be planted just about anywhere within the scene setting, from behind, below, and on top of props, to the furniture and walls. It is still important to use shock mounts when using these mics, which help protect them from vibration sound distortion. The plant mics were used frequently throughout the late 20’s and 30’s in film because the large, fragile ribbon microphones of that particular time had to remain stationary.