Recording - February 2013 - 70

When it comes to microphone selection and placement, the unfortunate reality is that many of us do not have a limitless mic locker filled with all sorts of sonic options. Even a well-stocked locker is never quite full enough. Truly, how many mics does a person need? (Answer: Just one more!) There are a number of multi-mic techniques for capturing a stereo sound source including XY, ORTF, Blumlein, and Mid-Side (M/S) recording. There’s also the second-mic-over-the-acoustic-guitarist’sshoulder technique that can be useful for capturing another perspective on a stellar performance. But for all of the benefits offered by these techniques, they all have one restriction: What’s a person to do when only one mic is available? Or perhaps you’ve just captured the greatest performance with two mics, only to find on playback that one of the tracks is unusable, for whatever unfortunate reason. What then? Though you won’t get a perfect replica of a multiple-mic recording, you can simulate a multiple-mic recording with only a single mic and a little mixing trickery. We are supplementing this article with a few audio examples, at www.recordingmag.com/resources/resourceDetail/393.html Before we get to the technique, let’s take a moment to explore how multiple mics add spatial depth to our recordings. Sense of space How do our ears help us in sensing the space we are in? We take clues from the timing of sounds that arrive at each of our ears. If a sound arrives in our left ear a microsecond before our right ear, our brain will interpret the source of the sound to be slightly to the left. If sound arrives predominantly in our right ear and the left ear hears nothing but reflections, we understand that the sound is hard to the right.

By Kevin King

Fig. 1

Volume can also be an important clue. If one sound is louder than another, we understand the louder sound to be the closer source. With complex reflections our brains can even identify sounds as being in front, behind, or even above or below our listening position. (For more on this, look up the term “Haas effect”.) Multiple-mic techniques simulate this by capturing and blending multiple perspectives of the sound source. Placing microphones in specific locations and positions captures the sounds bouncing about that particular recording space. When the recorded track is played back the sound is combined from the multiple perspectives, recreating the timing and reflections as they were recorded. Our brain then interprets the slight delays and reflections as spatial depth, recreating an acoustic image of that source in that space.
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The challenge then is to trick our brains into thinking that we have multiple perspectives on the sound source even when we may only have one. Fortunately, the brain is easily tricked. With only one recorded channel, we have only one perspective of the sound source. This one perspective will capture the direct sound plus any reflections in the space. However, because there is only one sound to arrive at our ears, there is therefore limited depth. We can pan the sound left and right, but that single perspective will lack the spatial clues that a second perspective would offer. So let’s add that second perspective, shall we? Faking an M/S recording To use this technique you’ll need a DAW that can split a mono track into multiple channels and then recombine them into a single channel (perhaps with a bus) later. Virtually every DAW out there should be able to do this. For this demonstration we’ll be using PreSonus Studio

http://www.recordingmag.com/resources/resourceDetail/393.html

Recording - February 2013

Table of Contents for the Digital Edition of Recording - February 2013