If you’re a home recorder on a tight budget, the answer to this question might be “your new best friend.” Shotgun mics are what you need for tight recordings outside a studio.
The “shotgun” refers to the shape and direction of the microphone, not the precision. A shotgun sprays pellets everywhere, but a shotgun mic is much more focused.
These mics are super directional, with a narrow frontal lobe that blocks out most sound from the sides. They have a nice crisp sound that works great in locations with a lot of ambient noise, like newsrooms, bars, comedy shows, and sporting events.
More importantly for us, they are great at recording in home environments. With only one direction to worry about, soundproofing is not that important. Instead of building a whole studio room, you can just build a little corner booth and use a shotgun mic.
Like a gun, a shotgun mic is a long tube. The actual element is located well back from the front of the tube, and the only way for sound to enter is from slits on the front or sides of the tube.
You might be thinking, “Why are there slits on the side?” It kind of would make sense to just seal off everything but the front, right?
Unfortunately, that doesn’t work. Metal is not soundproof, so a sealed tube would still transfer sound from the sides right through to the element.
That’s where the genius of the side slits come in. The slits break up sound from the sides into dozens of sound waves with similar frequencies, but at slightly staggered starting positions. This means that the sound, passing into the tube, will split into signals which are out of phase and so cancel most of itself out.
Problems with Off-Axis Sound
Any sound not coming from directly in front of the mic is “off-axis.” This will include any instruments, as well as the echo of any vocals. Most off-axis sound will wipe itself out, but the sounds that does get through will be very coloured. If you strum a guitar while singing, a shotgun mic will likely mess up the track.
Short vs. Long
Longer shotgun microphones offer a wider range of interference. Although short tubes are coming into style, they just don’t cut it for low-frequency ambient noise like, say, traffic noise outside your house. A longer tube provides space for all noise to interfere with itself and cancel itself out.
When buying a shotgun mic or any mic always choose function over appearance.