Good sound recording doesn’t start with equipment, it starts with understanding your recording environment, which in turn will inform which kind of mic you may choose and how best to deploy it.
Step one is to listen! Even in an apparently silent room, there are likely to be sounds like air-conditioning units, extractor fans or buzzing lights, or perhaps distant traffic noise getting in through an open window; but unless we deliberately listen for them, our ears, or rather our brains, have a habit of blocking these normally insignificant sounds out. If any of these issues are present, switch off the offending appliances and close any open doors or windows.
Next, clap your hands and listen to the sound of the room itself, the room acoustics. If you’re lucky, the sound of your handclap will die very quickly, as the acoustic energy produced is absorbed by carpets, soft furnishings and curtains, with very little reflecting back into the environment. If, however, there’s considerable audible reverb, you may want to try calming this down before you begin. If you do a lot of corporate video work, it’s worth carrying a few acoustic blankets, like the Producer’s Choice products from vocalboothtogo, which are surprisingly cheap for a specialist product. Failing that, some heavier domestic quilts and, if the floor is bare, a nice thick rug will also help to stop reflections from below.
At this point, if you can’t reduce reverb problems at the source, you may decide to use a lav mic rather than a shotgun. A lav mic can be placed very close to the target sound source, without being obvious in the frame, reducing the ratio of room reflections your mic is picking up, in relation to your talent’s voice. It’s also worth noting that if there is a lot of room reflection, shotgun mics can produce an oddly coloured sound due to their interference tube design.
If you’re shooting outdoors, you might have little or no control over environmental noise, but again, understanding what you’re up against might help you decide on mics and mic placement. For example, if you’re shooting in an area with lots of traffic noise, a lav mic is the obvious choice, although a shotgun mic, positioned side on to the road, would do a great deal to reject the unwanted sound.
One last note on sounds you don’t want on your recording: make sure everyone involved has turned off their mobile phone or put it into flight mode!
If you’re shooting indoors, you have more control over your filming environment, and probably more setup time than if you’re working outdoors. If you can, run cables to your mics rather than going wireless, as this should improve sound quality, as well as being more reliable.
If you’ve chosen to use a shotgun mic, boom this in overhead, in front of your talent, angled at their chest rather than directly at their mouth. This placement provides a good rich sound, reduces the chances of any plosives or popping and also allows some back and forth movement by your talent without going off-axis. Have the end of the mic just out of frame, so that it is in as close as possible to the interviewee without being visible in the frame, and check that it isn’t casting any unwanted shadows on your talent or background.
When booming a mic like this, make sure that your mic stand is up to the job and be aware that even a small weight on the end of a boom exerts a lot of torque on the stand. A falling mic stand definitely won’t impress your talent, particularly if it hits them on the way down! If possible, use a C Stand with a boom pole attachment, as the bases of these are very heavy. Alternatively use a purpose-built overhead mic stand that has a counterweight. If in any doubt as to the stability of your stand, leg weights are also a good idea to add ballast.
If you’re working with a lav mic, clip it to your talent’s clothing, around 8-10 inches, or 20-25 centimetres, below their chin. Ideally the mic should be fairly central as this means that they can move their head to either side without affecting the sound too much.
Try to hide lav mic cables under your talent’s clothing, as the point of having a tiny, unobtrusive mic is lost if there is a load of visible cable in view. Make sure that both cables and wireless transmitter are secure because any movement of these will transfer to the mic and will be audible on your recording. Tie a broadcast loop in the lav mic’s cable, which is a loose loop, fairly near the mic itself. This helps to absorb the effects of the cable getting tugged if it gets caught. If time allows, it’s not a bad idea to take the lav mic cable to your talent’s clothing, as this will help stabilise it as your talent moves around.