Audio quality is a critical component of a successful video. In fact, so much so, that most viewers will put up with lower quality video if the audio is up to snuff. For the kinds of videos we’re discussing here, good audio quality means loud and clear voices, minimal background noise and minimal or no visual obstruction (you don’t want to see the microphone).
To make sure your subject’s voice is loud and clear, you need your microphone to be as close to the speaker as possible, so you’ll need to use an external microphone that plugs into your camera or an audio recording device. Placing the microphone close to your subject can also help minimize background noise, but other factors include the type of microphone, the volume and character of the noises and the distance those noises are from your microphone.
There are a huge variety of microphones that come in various form factors and are available at prices ranging from a few dollars to several thousand, but for video, we can narrow that massive field down to two basic form factors: lavalier and shotgun.
A lavalier microphone, which clips to your subject’s jacket, shirt or tie, does a good job of getting close to your subject. Your “lav” will either be omnidirectional — meaning it picks up sound equally from all directions — or cardioid — meaning it picks up most of its sound from the front of the microphone, with some pick up to the sides and none behind the microphone. A cardioid model will cause problems if your subject is very animated and tends to turn his or her head, but will do a better job at blocking out some of the background noise in the room.
Placement of a lavalier is key. In general, you’ll want to place the lavalier mic in the top third of your subject’s torso, either clipped to the button flap on a button-up shirt or to a jacket lapel. You may need to experiment some to see what works best for your microphone. If you can, have the subject feed the wire through their shirt or tuck in their jacket. If your subject moves around a lot, you’ll need to instruct them to take care not to brush against the microphone (or you’ll need to change the placement to work around this). You’ll also want to make sure their movements don’t create tension on the wire, which can cause unwanted noises and even damage the cable.
A shotgun microphone focuses on a very narrow area directly in front of the microphone, rejecting sounds from the sides, and is usually placed overhead of your subject on a boom pole. (This is not the only way to use a shotgun, but it’s the best way to get the mic close to the subject without it appearing in the frame.) A shotgun does a good job of isolating the subject’s voice while still maintaining some of the character of the room.
Your shotgun mic should be positioned overhead of your subject, just off camera, on a boom stand. For optimal sound, you want the microphone as close to the subject as you can get it, pointed past the mouth towards the chest. If your subject moves around a lot or faces different directions while talking, you will have some differences in sound quality. You may have to adjust your placement to accommodate. If you have more than one subject, you can position them slightly facing each other and position the microphone between them.
(For a good description of omnidirectional, cardioid and shotgun microphones, read this short guide from NPR.)
Both types of microphones are widely available with either eighth-inch (3.5mm) TRS connectors (a standard headphone connector) or a standard microphone XLR connector.
Microphones with TRS connectors are generally cheaper (and therefore usually lower quality), but are easier to use, as they can plug directly into your camera or smartphone. (However, you will need an adapter in order to monitor the sound while shooting if your camera does not have a separate headphone jack or if you are shooting with a smartphone.)
Microphones with XLR connectors are generally higher quality, but there are still options available at relatively low prices. However, unless you are using professional video equipment, you will need to purchase additional equipment, such as a Zoom H4n, to capture the audio from the microphone. If your camera has separate line-in and headphone TRS jacks, you can send the output from your recorder right into your camera and use the recorder as a backup/failsafe. Our camera has only a combined line-in/headphone jack, so we combine the high-quality audio with the video in Premiere Pro. (Here’s some additional reading from Wistia on shooting video with a dSLR and a handheld audio recorder.)