There are different kinds of microphones out there that perform different functions.
It’s always good to understand what a specific mic does so that you use it in accordance with its application.
If you’re involved in the world of audio production you’ve probably come across what are called Shotgun Microphones.
This post is going to get into what they are and what they do so you know them better and use them accordingly.
So many people have requested me to write about this microphone type and I’m going to grant that wish today.
With that said, what is the shot gun microphone?
Shotgun microphones are highly directional microphones with a tight pick up pattern that have to be aimed directly at a sound source for them to capture it effectively. Shotgun mics have a shotgun-barrel like shape which is why they’re called “shotgun” mics.
How a shotgun microphone works
In essence, a shotgun microphone simply operates on the principle of “waveform interference”.
Shotgun microphones have slots in the tube and the element is at the bottom of the tube which makes interference impossible.
The desired source needing to be recorded which is reffered to as the on-axis sound will pass straight down the tube and be picked up by the capsule unimpeded.
You may ask yourself, what are the slots on the tube for?
Well, the slots simply serve as the separate entry points for off-axis or undesired sound which will enter many slots at difference locations.
The slots are well engineered to be a different distance from the microphone so that when off axis sound enters them it will be out of phase with each other which tends to have them cancel out each other.
In fact, sound can either attenuate or blunt the sound coming in from the end of the tube in a process called constructive or destructive interference.
On-axis sound tends to be enhanced and off-axis sound tends to be attenuated or reduced.
Of course there are many limitations to shotgun microphones.
For example, by virtue of the mixing of the off-axis sound, there is lots of interaction of these sounds and they become somewhat “colored” or altered.
This effect is particularly prominent and audible when the mic is moving.
An additional issue is that short shotguns tend to work at higher
frequencies and are not overly effective with picking up the mid and low frequency sounds.
Another limitation, when used in a desktop arrangement, is that it is important and critical that the user stay “on axis” with the microphone.
This may leave the user feeling somewhat a “prisoner” of the microphone.
In general terms, longer shotgun microphones work better but are more sensitive to staying exactly on axis.
On Camera Shotgun Microphones
On-camera shotgun microphones have a shoe mount which allows you to attach them to a slide-in mount, typically used for mounting lights and strobes on top of the camera.
These mics are short in barrel, which makes them invisible in the video frame.
However, they have broader polar pattern than off-camera shotgun mics.
Off camera shotgun microphones
Off-camera shotgun mics tend to be more directional and have longer interference tubes.
They also have numerous phase ports to reject off-axis sound.
In most cases, these kind of mics are used in video production and are mounted on microphone booms to capture sounds from a distance.
However, this requires an experienced operator because a slight move off axis could potentially affect the sound recording.
Cell Phone shotgun microphones
These kinds of mics are especially designed for smartphones just as the name suggests. They typically have a shorter barrel and they’re not strict with operation making them usable for the average smart phone user.
Below are some of the uses of shotgun microphones
Shotgun microphones are the go to microphones for things like Speeches that require a microphone that can pick up on-axis signals without running into background interference issues.
These mics can be great if they pointed or aimed exactly at the speaker.
Talks in conferences
Most conferences involve many speakers who all usually participate in active dialogue.
This means each speaker needs to have a microphone that doesn’t pick up off axis sounds because if it does then the mic will pick up all the sounds of the other speakers.
Shotgun microphones are useful because they make it possible for conference dialogue to be carried out with ease.
Interviews also utilize the shotgun microphone because it allows the interviewer and interviewee to speak without the mic picking up background interference.
A shotgun is definitely a great choice any time you need to capture sound without any background noise.
It’s especially useful in crowded or noisy spaces where you want to isolate a specific sound source and capture it clearly.