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An Introduction to Microphones

The Neumann U47 microphone. Designed by Georg Neumann circa 1949. A brilliant design that has withstood decades of audio innovation.

Audio recording is superficially simple. Place a microphone in front of your subject, set the record levels – and you’re done! However reality is very different. Correct microphone selection, placement and technique is critical to good audio quality. And nothing will kill a production like bad sound.

We’re going to look at the types of microphone that are relevant when shooting video. There are many more types available for applications ranging from instrument recording to air traffic control. However we are primarily concerned with recording ambient sounds and especially voice. Spoken voice is a notoriously difficult thing to record well. It’s a sound we hear every day and are very well accustomed to. Any artefacts created by the recording process will quickly be noticed, and unlike vision, for which our brain commits huge amounts of its computational power to resolving, poor sound just plain drives us crazy!

Types of Microphone

Condenser Microphones
With a few notable exceptions a condenser mics’ natural home is the studio. They are normally powered externally and are the most sensitive microphone types. The classic Neumann U87 has been involved in the recording of just about every classic album since the 1960s and probably one the most recognisable microphones in the world. Like all condenser microphones, its high sensitivity isn’t always desirable. See dynamic microphones below.
If recording vocals in a treated room i.e. one with good acoustics you’re going to want to use a high-quality condenser.

Electret condenser microphones
These are a type of condenser microphone but can usually be powered by an internal battery. They offer quality that often rivals condenser microphones but allow more flexibility in their application – and their lower cost helps too. Most of the microphones videographers use will love this type. Handheld, lapel (lavalier) and shotguns all benefit from the high sensitivity and lightweight diaphragm of the electret condenser.
Some of the most popular shotguns mics include the Rode series NTG1, NTG2 and NTG3 and the Sennheiser modular K6/ME66 and ME67.

Dynamic Microphones
These relatively inexpensive and robust microphones are often the microphone of choice for voice-overs. Their relative lack of sensitivity means they will only record sounds that are adjacent to the microphone. If you’re recording a voice-over in a location other than a recording studio, with its acoustically treated walls and relative silence, you’ll want to use a microphone with these properties. Microphones like the ElectroVoice RE-20, Rode ProCaster, and the Shure .

Microphone directionality – polar patterns

Microphones vary in their ability to pick up sounds in relation to the direction in which they face. They fall broadly into three camps:

Non-directional (Omnidirectional)
The lapel or lavalier microphone is a classic application for an omnidirectional microphone. Typically worn on a tie, or as the name suggests, a lapel these small microphones combined a high sensitivity with their ability to record in all directions. At a wedding for example a lavalier placed on the groom will record not just his voice but also the brides and the vicars.

Unidirectional
A unidirectional microphone is sensitive in one direction only. There are typically used to pick up individual sounds whilst ignoring the other sounds around them. They are typically used the recording speech was rejecting the ambient sounds from other directions.

Shotgun
By mounting the microphone elements at the end of a long tube these microphones become very directional and have excellent off axis rejection. Slots in the length of the tube create standing waves which help cancel out sounds emanating from the sides and the rear.

For most event videographers their audio setup will be a combination of direct connected shotguns with radio lapel mics providing close-up live speech recording.

Applications

Type of microphone Notes
Live spoken voice Lavalier 

Shotgun

Direct or via radio 

Out of shot

On camera Shotgun
Ambient sound Omnidirectional
Voice-over Condenser or Dynamic Depending on room acoustics