This post is in response to an email I received recently. A reader of this site had seen a television feature about the nature sound recordist Gordon Hempton and thought it would make for a good blog post.
Actually I have met any number of nature sound recordists, including Mr. Hempton, so I think it appropriate to devote a blog post to this field even though I touched vaguely on the subject in the post “Sound Docs.”
Before I “name names” and give links to the artists’ websites (in RECORDING NATURE – PART 2), let me talk about recording methods used by nature recordists. Though all these methods are sometimes used in music recording, some of the less familiar ones are used more by documentary recordists, especially nature recordists, than by music producers and may not be familiar to some readers. If you have a good background in recording natural sounds and don’t need a refresher on the technologies, then skip right to RECORDING NATURE – PART 2.
MONO MIC (OFTEN “SHOTGUN”)
This is probably the most traditional way to record nature sounds. Long before digital recording, and even before stereo, nature recordists would take a portable monaural analog open reel recorder, such as those made by Nagra, and a single microphone into the field. Often long, quite directional, mics would be used to make one sound stand out a bit from the background. These were the same kind of microphones ultimately used in television and film production to record dialogue.
These mono sounds can be edited to produce recordings of individual sounds (such as of a special bird) or a soundscape (such as a chorus of birds on a tree). Sometimes several sound recordings are mixed to create a soundscape composition.
I have seen, recently, people recording mono nature sounds on their cell phones. These aren’t ideal for serious work but are amazingly good for what they are and are convenient. I am not aware of cell phones with built in stereo mics, though there are attachments for some phones that do provide a stereo mic.
Outdoors wind noise can be a big problem. Mics used in the field are usually used with windscreens which can range from foam or fake fur covers for the mics to elaborate, and very expensive, “blimp” style protection (for the worst conditions).
STEREO MIC
When stereo listening became popular nature recordists could take out stereo mics that would record two channels. Although this could be done by a pair of mono mics, the development of very good stereo mics made setups smaller and more portable. There are several ways to record stereo and maybe a future Audio Penguin post will describe them individually.
Most recently, stereo field recording got a big boost by the development of digital handheld recorders with stereo mics built in. Before solid state digital recording to flash memory was available, it was really not possible to build microphones into any kind of high quality recorder because the motors of tape drives or hard drives would be picked up by the internal microphones.
Many companies have developed quite high quality portable hand-held recorders. These are used heavily by radio reporters and by musicians wanting to record rehearsals or even make an “archive” recording of a concert. But nature recordists have also taken to them because of their convenience and decent quality for the price. For louder sounds nearly any of the popular brands — Tascam, Zoom, Sony, Olympus, Roland, etc. – will work, but if one is going to record very quiet sounds then one should be aware that some tiny recorders have fairly limited signal-to-noise ratio. That means that when the input volume is cranked up to record something quiet there might be quite a bit of “hiss” in the recording. Before buying such a recorder to use in soft sound environments it is worth testing out a particular recorder or at least reading the specifications (technical specs, not just the features) on the manufacturer’s website.
As with mono recording the individual sound files can be used separately or mixed to produce a kind of composition.
For serious work high end professional flash recorders are the best choice used along with a high end detached stereo mic, often on a small boom, along with whatever wind protection is needed. Higher end recorders have quiet microphone preamps and the best analog-to-digital convertors, while high end stereo mics pic up the widest range of frequencies with relatively low amount of self noise (hiss). For high end jobs, such as picking up nature sounds for film or television, I have often used a Sound Devices stereo recorder (about $3000) along with a Rode stereo mic (about $750). I also have a Schoeps stereo mic (about $3800). There are other very good combinations also with high end recorders ranging in price from about $700 to $8000 and stereo (or binaural – see below) mics ranging from about $500 to $9000. Again, I would urge the reader to consult with a professional or read up on technical literature before making such a major purchase. But it is worth learning and practicing with hand-held flash recorders (either using the mics built into the recorder or an external stereo mic). You might be pleasantly surprised with the capability of many for field recording.
BINAURAL MIC
A good discussion of binaural sound can be found in the Audio Penguin post titled THE ENCOUNTER which describes a Broadway show which used binaural sound. That method provides the most accurate stereo imaging possible, way better than traditional stereo, though playback is limited to either headphones or crosstalk cancelled speakers with the listener sitting in the very narrow “sweet spot” in front of the speakers.
Recording is often done with a “dummy head,” a microphone that looks like a human head but has microphones in the ears. These tend to be expensive, but there are tiny binaural mics, some surprisingly inexpensive, that one can put in one’s own ears, like earbuds, to capture the sound as shaped by one’s own head. Of course a disadvantage of this later method is the recordist cannot monitor the recording with headphones while recording. So there is a bit of gambling involved.
There are also microphones that one can wear like small headphones over the ears. These do not provide as accurate a binaural image since the pinna of the ear cannot play as big a role as it should in shaping sound, but users of these types of mics point out that the resulting sound files play over a stereo speaker setup better than some true binaural recordings – and the sound of the playback in headphones with these over-the-ear mics is still pretty amazing.
Since nature recordists are often trying to capture an accurate documentary sound experience, binaural mics are probably used for that type of recording than for traditional music recording.
SURROUND SOUND
Surround sound is usually associated with movie soundtracks which include sounds coming from the front as as well as toward the sides and even rear. Home theatre systems provide this theatrical experience in home though it was originally developed for theatre showing of films.
The sound experience in surround sound does not necessarily provide a truly accurate sound image, like binaural does, but can be thrilling since one is experiencing sound from multiple directions. This process, usually requires many microphones though at least one hand held recorder, the Roland R-26, has surround mics built in.
But some documentary recordists are creating a different kind of surround sound: the sound installation.
A good example was an installation I heard at the Invisible Places conference held in April (2017) on Sao Miguel island in the Azores.
In this installation the recordist had recorded specific sounds at different locations on the island. Sea waves one place, birds another, etc. (I don’t remember all of the sounds.)
Each sound was created as a separate (long) loop. In the gallery there were several loudspeakers (I am remembering 6-8) located around a large area. Each speaker played one loop. As in nature, there was no intent to synchronize the loops, each played independently without a multi-channel “master” recording.
Walking around the gallery near each speaker was a kind of “flying” around the island to go from sound to sound. But one could also produce an individual “mix” of the sounds by standing in a certain relationship to the speakers. Most of us who visited this installation spent quite a bit of time in it (nearly one hour for me) exploring the possibilities. This is another kind of “surround” sound that is a big departure from what that means for film sound.
CONTACT MIC
The vast majority of sounds are recorded by microphones having moveable diaphragms that vibrate when hit by sound waves. These waves are nothing more than vibrations of air molecules: a succession of compressions, where the molecules are pushed closer together, and rarefactions, where the molecules are spaces farther apart than in silent air.
But sound also travels through denser materials, sometimes more easily than through air. As a child I watched Western movies where someone would place his ear on top of a railroad track to see if a train was coming, since the sound of the heavy train on the tracks would carry more easily and farther than the sounds of the train through air.
Sounds that travel through dense materials can be pickup up by contact microphones, flat mics that are fastened to vibrating materials in order to pick up those vibrations directly. Musicians sometimes use these on the sound boards of pianos or acoustic guitars, but nature sound recordists find them useful for a whole range of materials. Also, since they don’t pick up from the air, sound vibrations from a vibrating surface can be picked up in a noisy atmosphere where ambient sounds would interfere with the pickup.
These mics usually consist of a flat piece of piezoelectric material which produces a small electrical current when stressed (as from sound waves). I first met one of the sound collectors I will highlight in part two of this post, Jim Metzner (producer of the daily short radio program “Pulse of the Planet”) when he phoned me to ask me if I could help him build some contact mics. They can be built quite inexpensively, since piezoelectric elements can be bought inexpensively from many science supply stores. However, for optimum quality they should be used with microphone preamps designed for their impedance rather than the standard mic input of a small recorder. The best contact mics can be bought with a matching preamp. A mic that is often preferred for high end contact mic recording is the Barcus Berry 4000 Planar Wave System (about $350 or less). Although designed for use recording pianos they are used by nature recordists wanted high end performance.
PARABOLIC MIC
If one wants to record bird songs one quickly finds there is a serious problem when trying to get a microphone close to birds: they fly away. A parabolic mic is usually made of plastic and looks like one of those small satellite dishes such as one uses to get Dish TV. (see photo). But instead of focusing radio waves from a satellite onto an antenna, they focus sounds onto a small microphone. They come in a variety of sizes and prices but the one shown, made by Wildtronics and designed for nature use, costs about $700. These can get very decent birdcalls even 50 or 100 feet from a bird.
You may have seen these kinds of mics used in spy movies where one will be placed in an open window to record conversations on the street a block or so away. (Unless you are a licensed detective or law enforcement officer I don’t recommend this kind of recording since one could get in legal trouble.) But they are good for many nature sounds though, to keep the dish size small, most cannot record extremely low frequency sounds.
HYDROPHONE
Finally, we finish our “meal” of nature mics with the fish course. A hydrophone is simply a microphone designed to be used under water. These are not terribly expensive ($150 or so) and not only can be used to capture the sounds fish make but also such sounds as the melting of glaciers. Sometimes they are used out of water to record sounds underground (such an ant colonies) in which case they are called geophones. Some models can be used for both applications.
In PART 2 of this article I will highlight a few sound collectors who do lots of nature recording. Some have lots of CDs available and others put their sounds online. But I hope this article has given you a good overview of the technologies nature recordists use.
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