Recording Nature in 3D
Binaural Audio is Growing in Popularity
Hi all! My name is Lang Elliott and I am the founder of the Music of Nature publication. I am a professional nature recordist with a passion for collecting spacious 3D binaural soundscapes. For those who are unfamiliar with binaural recordings and why they appeal to our senses, I have decided to explain what all the fuss is about, and why binaural recordings are gaining in popularity.
What is Binaural and How Does it Work?
In brief, “binaural” refers to hearing with two ears, as we humans do. What is amazing, if you think about it, is that we experience a deliciously spacious three-dimensional sound environment, yet we only have two sound receptors, one each side of our heads. How is this possible?
Our brains have evolved the ability to construct an accurate 3D sound-field experience from the information fed to us by our two ears. The three most critical “binaural cues” that our brains must receive include the following:
- Intensity differences of incoming sounds between the two ears
- Time arrival differences of incoming sounds between the two ears
- Phase differences of incoming sounds between the two ears
Our ability to properly decode and interpret such cues is so extraordinary and reliable that we trust our hearing without question, truly believing that sounds come from where we think they come from, even when we are unable to see the actual sources.
Binaural Recording :
“Binaural recording” refers to using a microphone setup that simulates the human listening apparatus, with two mic capsules placed about 7 inches apart (as are human ears), and separated by an absorbant barrier resembling the human head. From a purist standpoint, the two capsules would also be placed within flexible silicone or rubber ears that look and feel just like human ears.
Theoretically, a two-channel soundscape microphone setup of this design will collect the same critical binaural cues that our ears collect, allowing the listener to experience the same extraordinary sense of space that our natural hearing provides. In fact, the listening experience is often shocking to someone first encountering it … it is as if you are actually there, in the three-dimensional environment in which the recording was made, literally surrounded by a spacious and immersive soundscape that expands outward as far as the ear can hear.
How to Listen:
For our brains to process a binaural recording properly, it is imperative that the left ear hear only what the left microphone has recorded, and that the right ear hear only what the right microphone has recorded. This is best accomplished by wearing headphones, which effectively isolates the two channels. And that’s precisely why we say that binaural recordings are “optimized for headphone listening.”
Speaker listening has inherent problems when it comes to binaural recordings. With the speakers placed in a conventional equilateral triangle relationship to the listener, both ears will be hearing sounds from both speakers. This results in considerable “crosstalk” between the channels and causes significant degradation of the “binaural cues.” The result is an inferior sense of space and distance, although binaural recordings may still sound great over speakers. In any event … if you desire the best experience, please use headphones!
Why the Sudden Interest?
Binaural recordings have been around for a long time, but (until recently) they’ve never really been embraced by the mainstream audience, primarily because very few people were into using headphones. But that is no longer the case. As mobile devices such as smartphones have taken over our lives, more and more people have come to rely on headphones or earbuds for personal listening. And this has spawned a tremendous upsurge of interest in the binaural listening experience.
By accessing recordings via the internet or else mobile apps (like Pure Nature 3D Audio), listeners can literally “escape into nature” wherever they happen to be, especially when modern noise cancellation headphones are used to suppress ambient noise. Imagine relaxing on a couch at home, or even while working on your computer at Starbucks, gently surrounded by the soothing voices of the natural world!
Binaural Microphone Setups
From a purist standpoint, the most accurate and “true” binaural microphone setups closely resemble a human head, with microphones embedded deep inside natural-looking “ears.” This makes good sense, but there is an obvious problem with the concept: human ears vary considerably in shape and size!
Furthermore, new research has shown that even slight modifications of an individual’s ear canal significantly degrades one’s ability to accurately judge the locations of sound sources, especially in the vertical plane. So it is virtually impossible to build a “one-size-fits-all” dummy head microphone. In the end, a particular design that works great for some folks may not work nearly as well for others. That said, well-designed dummy-head mics do indeed produce extremely pleasurable and realistic listening experiences.
Without question, the most famous dummy-head mic is the Neumann KU 100, which costs a whopping $8000. It predecessor, the KU-80, was invented way back in 1973 and was initially used for radio drama productions:
More affordable dummy-head mics are how hitting the scene, such as this one from Binaural Enthusiast, which runs about $500:
An impressive line of binaural mics are now available from Inari Audio, ranging in price from around $1000 to $3000, depending on features. I’ve been following the development of these mics, and they sound great; I even plan to get one myself:
Without doubt, the most inexpensive approach to recording binaurally is to use miniature mics placed in one’s own ears. The idea is simple … use your own head and external ears, as opposed to using a dummy head with ears. And the results can sound great, especially if you want to record binaurally while on the move.
There are quite a few in-ear mics to choose from these days. One attractive option is the Ambeo Smart Headset, produced by Sennheiser and costing around $300. It plugs directly into an iPhone:
The quite affordable Scenes Lifelike microphone (100$) also plugs directly into an iPhone, and sounds pretty darned good!
The binaural mics from Sound Professionals have long been a standard. They don’t plug into iPhones, but they can easily be used with small portable tape recorders such as those made by Zoom, Tascam and Sony. Prices are in the $100 to $300 range:
The term “quasi-binaural” is often used to refer to binaural mic setups that don’t employ a dummy head with flexible ears. While this may seem to be a bad thing, in actuality many of these setups produce superbly spacious 3D recordings that are comparable to those produced by “true” binaural mic setups.
Perhaps the most popular quasi-binaural microphones available today are those developed by 3DIO, with prices ranging from $500 to $2000. While there is no “head” between the ears, the mics are spaced correctly and mounted in rubber ears. While the ears are somewhat of a gimmick when used in this way, the microphones produce quite acceptable 3D sound.
My Favorite Setup
You’d probably guess that I use a dummy-head for recording. But that is not the case. While I’ve experimented with them, my preferred setup is actually a quasi-binaural housing developed by entrepeneur Michael Billingsley and sold for many years by Crown International. It was referred to as a “Stereo Ambient Sampling System” (SASS for short), and produced a very spacious 3D quasi-binaural effect. Unfortunately, the mic housing is no longer available commercially.
Basically, the housing simulates the human head, placing mics about 7 inches apart, with a foam baffle in between. The mics are mounted flush with flat surfaces that impart a PZM (pressure zone microphone) effect that yields additional gain without accompany noise.
I purchased two SASS units many years ago, retrofitted them with high-quality Sennheiser MKH20 ominidirectional microphones, and loved the result so much that I’ve never been strongly tempted to switch to a different setup. The 3D effect sounds great to me (and to others) and the setup is lightweight, resistant to wind (with the addition of a wind cover), stable in inclement weather, and easy to deal with in the field.
Here is a picture of a brand new SASS housing (with inexpensive built-in mics), before being retrofitted with MKH20s:
And here is a pic of one of my setups today. It’s rather beat-up looking … I had to replace the foam insert and made a mess of it … but it’s still 100% functional:
Last but not least, here is a pic of me in the field, with my trustworthy companion at my side … a love affair that has lasted over 25 years!
Well, that pretty much covers the subject. I trust that you now understand the basics of binaural perception and have a working knowledge of the various binaural and quasi-binaural microphone setups that produce supremely spacious listening experiences over headphones.
If you own an Apple mobile device and would like access to over 13 hours of superbly spacious 3D nature recordings collected by Lang Elliott, please check out Pure Nature 3D Audio, a FREE application for Apple mobile devices.