Microphones – Understanding Sound
- Tea L
- Aug 10
- 5 min read
When it comes to recording sound, we are mostly talking about two pieces of equipment; the microphone and the recorder. (Not counting cables, mounts, etc.) So, in this article I’m going to try to give you the run down of the common microphones involved in audio/visual work. We’ll come back and cover how best to use them in a separate article.
(If you’ve read through the camera articles, this will be much simpler than that.)
The Utilitarian Quick Reference
Condenser mics are more sensitive, but require power and are more fragile.
Dynamic mics deal well with high noise levels but are less sensitive.
Shotgun microphones excel at cutting out background noise when used properly, but keeping your subject in the pickup pattern can be tricky.
Lavalier (lapel) microphones eliminate the worry of having the camera/microphone too far away from the subject, however they can be tricky to place while ensuring good sound.
Vocal mics provide exceptionally full audio quality, better than the shotgun or lavalier, but cannot be hidden or rendered unobvious when used in video.
Microphone Technologies
Microphones can be broken down into multiple types and subtypes, so we’re going to start at the highest level here and discuss condenser vs dynamic microphones. These are two technologies that underpin most all mics that you will encounter when filming.
Condenser Microphones are by far the most ubiquitous when it comes to microphone types commonly used in filmmaking; shotgun microphones and lavalier / lapel microphones.
Condensers use an electrically charged membrane, like the one in your ear, to detect changes in pressure (a.k.a. sound waves) and convert those into an electrical signal which is converted by your recorder into digital data.
These microphones require power to work, meaning either a battery or power delivered through the mic cable (a.k.a. phantom power or plug-in power.)
These microphones are typically more sensitive, meaning they will pick up quieter sounds and speech down to a whisper.
However, this also makes them less tolerant of very loud noises and more likely to pick up unwanted sounds. (More on this later.)
Dynamic Microphones are more common in live music, voice over and studio applications.
Dynamic microphones use a simpler mechanical design for their membrane, but the mic still generates a current that is sent to your recorder for digitization.
These mics do not require power and are typically less fragile than their condenser counterparts.
Their durability and lower sensitivity means that they excel at cutting out unwanted background noise in loud environments, assuming the source they are recording is strong enough to be heard correctly.
In some cases, sound engineers will use other devices along the signal chain to amplify these microphones in order to compensate for the lower output signal. (i.e. a Cloudlifter or Fethead.)
Now that we understand the basic technologies behind microphones, let’s discuss another basic aspect, pickup patterns.
Pick up Patterns
A pickup pattern is a visual representation of where the microphone is designed to “pickup” the sound you want to record and where it designed to “reject” other sounds. This varies between types of mics and also between individual models. Let’s start with a simple and specific example: the shotgun.
Shotgun Mic Pick up Pattern
This is the only pickup pattern that is named to match a specific design of microphone.
As you can see it shows that the microphone “picks up” sound primarily in a thin cone directly in front of the microphone.
This means that this microphone is intensely directional, aiming to “reject” as much sound as possible outside that cone due to the thin pickup pattern.
We can also see that it will pick up a little sound directly behind or beside it. This is a bi-product of the very specific design needed to accomplish this directionality.
Omni Directional Mic Pick up Pattern
This pattern can be found in many mics, like some lavalier microphones and microphones aimed at ambiance recording.
This demonstrates that the microphone is designed to pick up sound in, as close as possible, to a 360° sphere around the microphone. (Though pickup will always be slightly better in front then behind.)
This can be great for beginners using lavalier microphones, as it means their clipped / taped position on the subject doesn’t need to be as precise.
However, it also means that this microphone does not “reject” sound from any direction, making it pick up more background sound or reflections (echo).
Cardiod Pick up Pattern
The cardiod pattern is named due to its heart-like appearance.
This demonstrates that the microphone primarily picks up sound directly in front of the microphone as well as to the sides, while rejecting sound directly behind it.
This pattern can be found in lavalier mics, but it is especially present in vocal microphones.
In a lavalier, a cardiod pattern means you have to be better at positioning the mic, but you cut out more background noise when recording.
An advantage for vocal microphones, is that this pattern means that two hosts can sit opposite each other at a table and their voices will stay more separated if recorded to different tracks. Allowing them to be edited or mixed independently.
There are also other patterns like Hypercardiod, Bi-Directional, etc. but they are less common in the types of mics most used for cinema, where you'll be seeing these 90% of the time.
A general note about pickup and range
Now just because a microphone’s pick up pattern shows that it covers everywhere in front of the mic (cardiod) or in a selective cone (shotgun) that does not mean distance from your mic to the sound source does not matter. Microphones all have effective ranges but the golden rule is always:
The closer the microphone the better the pickup.*
in most cases, as long as you are not pressing your lips to the microphone. See the post on proper usage of microphones for more.
Types of microphones (from a filmmaking perspective)
The two most common microphone types used in film are shotgun mics and lavaliers, if you include new media like streaming you could also say vocal mics fall into this category. However, shotgun mics and lavaliers are specifically designed to be unobtrusive visually for narrative filmmaking.
The shotgun microphone
A tube shaped mic with rejection ports on the side, these are functional to help keep its pickup so directional.
Typically the longer the tube / more ports, the more directional.
Shotgun mics are fantastic at cutting out background noise, assuming they are pointed correctly at your subject and used at an appropriate distance.
However, this directionality can make it difficult to keep the subject properly “on mic” if they are moving or turning their head.
Shotgun mics are also designed to be used from off-frame, originally via boom pole. So while a shotgun mic performs its absolute best at ~6” from the sound source, most also work well up to 1.5 feet away.
The primary downside to shotgun mics is “handling noise”, these microphones are very sensitive to any physical shocks and must be used with shock mounts at a result.
Secondarily, the small pickup area on the rear of the microphone can exaggerate reverb (echo) in very small "live" spaces.
The lavalier microphone
A small capsule microphone attached to a cable, in the modern context it is usually assumed that this microphone will run to a wireless transmitter / receiver setup, leaving the subject free to move.
These microphones can come in Cardiod (better for noise) or Omni-directional pickup patterns (easier to place.)
Lavaliers most often come with a clip they can be attached to that is designed to be clipped to a buttoned shirt or blouse. (Allowing the cable to be put through the button holes and hidden from view.)
In fiction filmmaking the lavalier is often taped to the subjects body or inside clothing to avoid the audience seeing evidence of the microphone on screen.
The ideal distance for a lavalier mic is ~6”, roughly the distance from a person’s mouth to their sternum. Alternatively, hiding a mic behind an ear pointing towards the mouth or in the brim of a hat is not uncommon, though trickier.
The main difficulty with Lavaliers is keeping them oriented correctly and avoiding clothing sounds / wire sounds from a moving subject.
In the following article we’ll discuss types of recorders and then finally we’ll cover the best practices for recording sound.
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