User:DeeBee

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Ahoy...I'm just going to dump stuff on here until I figure out if it belongs anywhere on the existing pages in this fine wiki...or until I get the 'audacity (sorry) to create my own new pages /sar


Audio Fundamentals: Microphone Techniques for Voice

Whether you are recording voiceovers for a synch-sound or video project, recording interviews, or simply narrating a story for a kids podcast, the subject of microphone technique is your very first link in establishing a quality chain for good acoustic recordings. Of course, the expansive subject of mics for musical instruments merits it’s own separate discussion, but many of the fundamentals below will also apply to micing up any other acoustic sources.

First is your microphone selection, and while you might not be able to afford a $4000 German condenser or a vintage capsule, there are still many very good dynamic and affordable condenser microphones out there that will give you very good results for only a nominal cost, and you won’t have a coronary arrest if they accidentally drop off their stand. A condenser mic will require phantom power from a mixxer, and is much more delicate and easily overloaded, so your best bet is to start with a cheaper and more rugged dynamic mic. Although most people will go for the more directional cardoid pickup pattern to reject more off axis sound, keep in mind that omni-directional mics have a smoother frequency response (especially in the low end), and are less susceptible to wind and breathing noises. Small clip-on ‘lavalier’ type mics are mostly omni-directional.

Speaking of small equipment, the little 3.5mm microphone connector at the back of your PC might be fine for the headsets or cheap lapel mics used by your average Messenger or Skype type of application, but rest assured that the quality of those recordings will make your finished product stand out in a way that most people won’t appreciate. Unless you are purposely going for a lo-fi transatlantic sound, then you should get a proper mic, which ideally uses the 3 prong connections of a balanced XLR cable to limit any noise being picked up by the cable. Bring this signal from a mixer or pre-amp into your PC via it’s line level inputs, or even take the RCA outs from the back of a cassette tape deck if you’re really stuck for a way to use an un-balanced ¼-inch microphone plug. Just remember to put the machine in record to set your levels and monitor the output (not tape) to get a usable signal. This is as far as we will go down the signal chain for now, since we are focused on creating the best initial quality possible at the point where it all begins. The microphone.

So whether you’re going to use a borrowed condensor, a battered SM-58, or even something leftover from a busted karaoke machine, you should always be looking around the room you wish to record in for the best acoustic space in either the immediate or the adjoining space. Now put on your headphones and consider the environment that you’re recording in. Turn up the gain (initial volume) abit, and have a –careful- listen to your recording environment, and try to eliminate any environmental noises, within reason. Remember that the sound of traffic or background music might sound cool, but later on could make any edits to your track sound choppy or abrupt. It’s better to record such ambiances separately and then loop them in later as separately mixxed tracks for maximum effect. Listen carefully for any fans, AC units, or refrigerators that you can temporarily turn off. Can you throw a blanket over that PC during the recording if it has a noisy powersupply fan? Even fluorescent lights can introduce noise that you will hear later if you’re using a good microphone or high enough gain settings.

When selecting your environment, try to find rooms with lots of drapes or curtains, and remember that carpet is great for soaking up reflected sound, as is plush upholstery. Avoid getting too close to any hard surfaces, especially if they are parallel or facing each other. Try to record at odd angles to such surfaces and avoid pointing your mic at 90 to walls or 180 degrees between close walls if you must be around big reflective surfaces. Also be careful about microphones stands on tabletops since not only will table noises trasmit up through the stand (try a few mouspads underneath to dull this effect), but you can also get noticeable phase cancellation effects if the mic is picking up alot of short reflections. Ask any guitar player friends to demonstrate what 'phasing' sounds like, and try to avoid it when making clean recordings.

So to summarize mic placement, whether standing with a handheld or clipping to a stand, try to stay away from walls and especially corners, unless you’d like to purposely over accentuate some lower frequencies. Tabletops are tricky, and you should point mics as directly away from the surface as possible to limit phase interference between the direct sound and any short reflections. The ratio of direct to reflected sound in the room (you know...that overly 'roomy' sound?) can also be optimized by getting a mic as close as you can to the source without overdriving the signal. Remember that 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 make it harder to set optimum levels, so try to back off the mic a tiny abit for louder passages or emphasised lines unless you've got a decent compressor to smooth out the peaks.

If you’re doing handheld interviews for the first time, you should practice your grip by cranking the gain abit and listening to the handling sounds, to hear and learn what you can, and can’t get away with when moving about or griping the mic barrel. Wiggle the cable connection to check for any loose or intermittent connections, and either repair them, or at least coil the end of the cable into your grip to alleviate any strain on the connection itself, and tightly duct tape the connector to the barrel, and then tape the strain relieving coil to the mic as well. Depending on the quality of the cable you’re using, you might also notice that the cable itself is introducing noise if it bumps or taps against things. Without getting into the meanings of ‘self impedance’ and ‘leaking shields’, it should suffice to say that taping down your cable run, or at least eliminating movement is your first option, if you can’t repair or replace with a higher quality cable. If you need to run cable over AC power lines, then cross them at right angles to limit the inductance 'pickup' effect that you can get from runnign audio paralel to power cables. There are already too many ways to pickup a 60hz hum, so you can at least eliminate that one. Speakign of power, try to avoid using AC power outlest that have heavy motors (fridges, tools) drawing from the same circuit.

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 abit to see if that helps. As always, the simplest solution that is closest to the source of the problem is likely the best one.

NEXT:

Audio Fundamentals: Setting and Optimizing Levels