| Audio and Field Recording | ||||||||
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Field recording means different things to different people. For some, it may be a primary or adjunct tool for work in disciplines such as cultural studies and anthropology (indigenous peoples, folkways, etc.). Other recordists collect specific natural or manmade sounds for personal or professional work. Some use audio captured in the field as a supplemental or integral part of multi- and mixed-media presentations. And some musicians seek out sounds from outside the studio to blend into musical compositions -- either as components or as the "instruments" and "voices" of an entire composition. Among these different users, the biggest points in common
are that the activity takes place outside the studio, and that good
portable equipment is essential. Following are some observations
and experiences. |
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In the past, field recording equipment has followed other developments in electronics and audio-- the major difference being the need for portability. And although you could, in theory, take a phonograph cutting machine into the field (and some did), the appearance of wire and tape recorders really opened up the field. Reel-to-reel tape gave way (though not fully) to cassette recorders (more practical as noise reduction technology and better quality tape became available)...And then digital came onto the scene. DAT (digital audio tape), Mini-DAT, MiniDisc are all examples of digital recording systems that use some kind of media the must be physically moved or rotated past a record or read head. The most recent change has been the introduction of recorders that use solid state flash memory. A recent flash recorder to hit the market is the Edirol R-09 (by Roland). It uses SD/MMC flash memory cards up to 2GB. That 2GB gives a recording capability of between 110 minutes (24 bit WAV file sampled at 48 kHz) to 1,993 minutes (83 hours of MP3 files at 128 kbps). The R-09, lying down, has about the same footprint as one of the larger iPods, but is about twice the thickness. Other recorders in the same price category ($500 and under) include the Marantz PMD660, the Edirol R-1, and the M-Audio MicroTrack 24/96. All use Compact Flash (CF) cards and all but the MicroTrack are capable of providing standard 48-volt phantom power -- required for some condenser microphones. Below are pictures of the Edirol R-09 -- the recorder I use.
In concept, these recorders are the audio equivalent of the point-and-shoot (P&S) digital camera, but with one distinct advantage -- described in the next section.
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All of the recorders mentioned above come with internal or included mini-microphones for recording in stereo. These mics do a pretty good job for general recording. In fact, even the most compressed (lowest quality) MP3 stereo recording of a meeting will be much better than what you get from the typical microcassette recorder. But the characteristics and specifications of the built-in microphones are not always clearly described and may not be what you need for a particular task. Additionally, by being attached to the recorder itself, built-in mics make some placement options impossible. Here is where these new recorders offer an advantage: Unlike their conceptual cousins -- the digital P&S camera -- the flash digital recorders let you select what is perhaps the most important component of the recording stream; the microphone. The circuits and processes in the recorder are pretty much a known quantity. But to achieve specific recording goals you have the option of using the best microphone you can afford -- or borrow. Perhaps the most convenient external microphone to use for field recording is a single-point stereo microphone. That means that at least two microphone heads are installed into/onto a single microphone body and feed audio to the recording device, usually through a single cable. Prices range from around $50 to over $1,000. To some extent you get what you pay for, although the most expensive microphones are usually specialist models. Most single-point microphones are condenser types. These require a small current of electricity supplied by a small battery in the microphone, through phantom power from the recorder, or from an external power supply. Condenser microphones are very sensitive, which helps in many recording situations. But they are also more sensitive to wind/breath noise, and less expensive models are often poorly isolated from the mechanical noise that can occur when handling the microphone, or even when handling or moving the mic's cords. I first tried a Nady CM-2S ($120 to $150). One nice feature is the low frequency roll-off capability. This allows you to reduce some of the low frequency sound. It should be used judiciously, but in big spaces (like the underground Metro stations in DC) use of that feature either on the microphone or on the recorder (the R-09 has that option) keeps the "boominess" under control. Unfortunately, the Nady microphone I ordered was defective. The right channel recorded low and I had to add at least 4dB to the right track of the WAV files in the computer. Getting the two channels matched is important for recordings if you want to present accurate spatial relationships within the sound field. Further, the Nady had poor mechanical isolation, so handling noise on the mic body was a problem. Even taps on the mic cable 4 feet away were transmitted to the microphone as thumps. I returned it.
The next microphone, and my current primary mic, is the Sony ECM-MS957 ($180 to $300). This microphone is a whole step above the Nady and uses a different technique for capturing sound. Rather than using two (theoretically) matched mic capsules, the 957 has Mid/Side (MS) capsules for stereo panorama. The Mid capsule picks up monophonic sound while the Side capsule picks up left/right difference sound. Subtracting and adding the two capsule signals yield separate left and right channels, and also permits electronic adjustment of the pickup angle. You can choose 90 degrees for a single sound source or 120 degrees to pick up many sources, ranged across the sound field. The rotating Mid capsule can be pointed through a range of 90 degrees. This allows the microphone body to be vertically oriented, while the Mid capsule is oriented towards the horizon -- a configuration preferred by some recordists looking for a fuller sense of ambient sound. Or the Mid capsule can be oriented towards the front of the microphone in the more conventional configuration. The 957 comes with a very handy mic stand that allows the recordist to use the center column as a hand grip. Although it is supplied with a conventional foam wind sock, I also decided to buy a Rycote Mini Windjammer for additional wind protection. The 957 is somewhat sensitive to mechanical noise transmitted up the cable, and the supplied cable has a cloth covering that rubs and provides the noise -- I'll be trying one or two hand-assembled cords to see if that helps. There is a "junior" version of the 957 -- the ECM-MS907 ($75 to $100). This microphone is also a Mid/Side design with 90 and 120 degree selectable coverage. The Mid element does not rotate. It has a plastic body and some reviews note more susceptibility to mechanical noise. But priced a little more than 1/3 the cost of the 957, this could be a good option for many. It also might be considered when the recordist expects to encounter dodgy conditions (environmental or social). In addition to the single-point
stereo condenser microphones, field recordists have other choices in
both condenser and dynamic forms: Shotgun mics (mono and stereo),
cardioid, unidirectional, omni directional, binaural, and parabolic. For
example, if you are assembling a more complex audio work, you might
want to record general environmental sounds in mono, using an omni
directional dynamic mic like the decades-old and nearly
bullet-proof
ElectroVoice
635A. Other mono or stereo tracks could then be
mixed with that background. |
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Although you can monitor your recording by watching the VU meter or little bars on the recorder's display, that's not really telling you what is being recorded -- only that a bunch of sound is being collected. (For you photographers, this would be like trying to take a picture with a digital camera using the histogram instead of the viewfinder.) The goal is to isolate your hearing from the environment so that you hear only the sounds that the microphone and recorder are picking up. This is useful because you'll know whether or not you "got" what you were trying to get, and also what other sounds you managed to pick up along the way. Here are some approaches:
You can be sure that the light weight on-ear headphones and non-isolating in-ear phones will NOT be effective for field recording...There is just too much sound leakage.
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One of the main advantages of digital recording is the ability to transfer files with no loss of data (the quality of the audio) and to be able to manipulate the audio files on a standard computer. That can be a Windows machine or a Mac, desktop or laptop. Granted, the speakers on your typical laptop leave a lot to be desired, but you are covered because you already have a good pair of earphones (see section above). You may want to consider two different types of software:
Beyond
those quick suggestions there are dozens of programs available for
Windows and Mac that do some or all of whatever you might need for a
project. |
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Here are some early recording samples using the Edirol R-09 and the Nady mic, and a link to a multimedia project that used the R-09 and a Sony ECM-MS957 microphone:
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| (Product photographs courtesy of the manufacturers.) | ||||||||