Anchoring: Mic Technique

Mic Technique

 

Types of microphone

Whether you’re doing voice-overs for a synch-sound or video project, recording interviews, or simply narrating a story for a kid’s podcast, microphone technique is the first stage of your signal path, and it’s where good production value for your acoustic recordings will begin.

Omni-directional mics have a much smoother frequency response (especially in the low end), and are less susceptible to wind and breathing noises.

Placement

Once you've chosen your mic, you'll need to consider mic placement. Whether standing with a handheld, or clipping to a stand, or even resting your mic on something soft like towels or a big sponge (if you're REALLY stuck without stand), you should try to keep your mic or mics pointed away from very close walls, and at least a few feet away from any such walls, and especially kept out of any corners, unless you’d like to purposely over accentuate some lower frequencies.

Tabletops are also tricky, and you should point mic(s) as directly away from the surface as possible to limit another type of phase interference between the direct sound and any short reflections of the same sound off the tabletop. The ratio of the direct sound to the reflected sound in the room can also cause that overly 'roomy' tone if the ratio is too low. This can be optimized by getting a mic as close as you can to the source without overdriving the signal, since the stronger the direct signal is the less obvious the sound from room reflections will be in relation to it. Just keep in mind that this will also make it harder to set optimum levels with so many emphasized peaks, so try to back off the mic a tiny a bit for louder passages or emphasised lines, unless you've got a properly setup compressor to smooth out those exaggerated close proximity peaks.

If you’re doing handheld interviews for the first time, you should practice your grip (as well as your interviewing manner) by cranking the gain a bit and listening to the handling sounds to learn what you can, and can’t get away with when moving about or griping the mic barrel. Remember that a firm grip is best, and to always hold the mic towards your subject to catch any afterthoughts or interruptions, and only briefly speak your parts into the mic if you need to add anything to the recording yourself. Giving yourself an ‘off axis’ sound by only speaking into the side of the mic, will not only help differentiate you (from your subject) in the recording, but it will also leave the mic pre-angled at your subject in order to more quickly put them right back on axis, and not miss anything they say.

With dynamic mics you will notice what’s called the ‘proximity effect’ when you get very close to your source, and start hearing a noticeable boost in the low frequencies. This effect might be desirable for vocals, and can be modulated by moving in or away from the mic. This proximity will also exaggerate popping sounds and consonants such as P’s, B’s, D’s, and T’s. You can limit this effect by turning the mic slightly ‘off axis’ by placing or pointing slightly away from those explosive expletives that are being projected directly out from in front of the speakers mouth. If you’ve ever seen the fancy looking ‘polar patterns’ for your mic, you will start to see different ways to approach the mic as well for different response levels. For now though, you should simply point the most responsive part of the mics pickup pattern just slightly off axis to any problematic sources. For explosive voices or sensitive condensers you can also fashion a pop filter out of hosiery or thin socks by stretching them over a modified wire coat hanger, and placing that in front of the mic, but just try backing off the mic a bit to see if that helps first. As always, staying close to the source of the problem with the simplest solution is likely the best approach.

How many microphones to use

Be very careful if and when mixing more than one open mic signal together (perhaps in hope of creating a stereo recording), because any slight shifts in 'phase' of the common signal (caused by slight differences in the precise distance between your subject and either mic) can cause very audible phase cancellations once they are mixed back together. Try to stick to mono recording if recording one speaker only or perhaps even for a two person interview. This will sound more clear and coherent when mixed with into stereo with for example music, ambience or sound effects.

For large meetings it may still be useful to consider multi-channel recording, placing several microphones around the room, recording each microphone on its own channel. The multiple channels can be mixed down to mono later, selecting for each speaker whichever channel gives the highest ratio of speech to room noise. When post-processing, simply choose one channel for each speaker, mute the others, then mix down.

Be aware though that Audacity especially on Windows may not be able to record multi-channel from all hardware and that this may be very dependent on the audio drivers used. Multi-channel recording also increases CPU usage and disk space usage. Be sure to test the hardware in multi-channel mode in advance, as running out of CPU capacity could cause recordings to have drop-outs or fail completely.

Technical Issues

Dynamic Range

One feature of recording people speaking is uncertainty of recording level. Speakers vary in volume, and may not be aware of the best microphone techniques so for example may stand in different positions relative to the microphone. In some cases, such as meetings and conference recording, there may also be remote participants who are being heard through a radio or television receiver. The result is wide recording level variations that can be managed through better microphone placement and techniques (above), audio compression before recording (coming soon), or the good old fashioned 'riding' of input levels if you're feeling brave and confident enough that you won't ruin a recording with excessive fader/knob 'moves'. The best results would likely result from subtle applications of all of the above.

Human Issues

Speaking Technique

Generally the less attention speakers pay to microphones the better their talk, and a way to minimize awareness is to not even mention the subject.

Hidden microphones can put speakers more at ease. They still know the microphone is there, but not being repeatedly reminded of it helps.

A basic way to create a hidden microphone is to cover a black-colored microphone and its visible section of lead with a layer of lightweight open weave clothing.

Reluctant speakers can sometimes be enticed forward by informing them that they get to review their recording and can say no to its distribution if they wish. This approach is only suitable for some situations of course, but it does elicit more spoken material. Reluctant speakers tend to fear things that don't usually happen, and usually say yes to distribution afterwards.