Remember getting those red and green 3D glasses with comic books back in the day? Now, 3D movies in theatres (and in people’s living rooms!) are the next big thing, and they make the old 3D specs look like antiques.
Likewise, most people with a home theatre setup have their speakers set for 5.1 surround sound, but very few people are savvy to the most immersive, ear-tingling 3D audio format that’s actually even more accessible.
Binaural audio is the sonic equivalent to today’s ultra-immersive 3D movies, and it’s actually been around for ages!
And here’s the best part: when you listen back to a binaural recording through headphones, you can perceive sound the same way you hear it in everyday life: coming not just from left to right (like a traditional stereo recording) but also from front to back, above to below, and everywhere in between. That’s right, it’s three-dimensional – a full 360 degrees around your head.
And these days, since everyone and their grandma has an iPod or MP3 player of some kind, doesn’t it make sense to record music tailored to headphone enjoyment?
SO HOW DOES IT WORK?
Binaural recordings are made using a special microphone that simulates an average human head (such as the Neumann KU100 dummy head). Two omnidirectional microphones are built into the ear canals, which capture sound the way humans hear it by preserving the Head Relation Transfer Functions (HRTFs).
When a binaural recording is played back through headphones, the listener can hear what it sounded like to be standing at the exact spot where the microphone was placed.
WHAT ARE HEAD RELATED TRANSFER FUNCTIONS (HRTFs)?
HRTFs are what allow our brains to understand where the sounds around us are coming from. When sound waves reach our heads, our brain can detect the differences in volume and time delay between our two ears, which it uses to determine each sound’s location.
Because the microphones in the dummy head are implanted inside the ear canals, the sounds that they pick up are already naturally filtered by the shape of the head and outer ears – that is, they are already imprinted with the HRTFs of listening in the particular location where the recording was made.
Later, when we listen to the recording on headphones, our brain analyzes those HRTFs as if we were hearing them in the original space, which can make for incredibly realistic 3D recordings.
WHY DOES THE 3D EFFECT ONLY WORK WITH HEADPHONES?
In order for our brain to process HRTFs correctly, it’s important that the signal from the left microphone reach only our left ear, and the signal from the right microphone reach only our right ear. Listening through headphones is the easiest way for this to happen, and although it’s possible to set up speakers in such a way that it would work, headphones really simplify the process.
DOES THAT MEAN YOU CAN’T LISTEN TO A BINAURAL RECORDING ON SPEAKERS?
Absolutely not! Binaural recordings made with a KU100 dummy head still sound fantastic on speakers, but you just won’t be able to get the 3D effect. That’s because as the sound travels through the room from the speakers to your head, the left and right signals (from the left and right speakers) mix and your brain processes them with the new HRTFs of your listening space.
To summarize: When listening through speakers, you still get a great high-def stereo recording (and still with a much better sense of spaciousness), just not an immersive 3D experience.
DO YOU NEED ANY KIND OF SPECIAL EQUIPMENT OR FANCY HEADPHONES?
Nope! Any set of headphones will work, from the little earbuds that came with your iPod to high-end studio monitoring headphones. As with any audio equipment, the better quality the headphones are, the better it will sound, but the only requirement for the 3D effect to work is that the left and right signals go straight to your left and right ears, respectively. Simple!
SO WHY HAVEN’T I HEARD OF BINAURAL AUDIO BEFORE?
Binaural audio has actually been around for a long time (1881 in fact), but has never been a major music industry format for a few reasons:
First, to preserve the HRTFs of the binaural recording, you can’t heavily process the audio. That means that the now-industry-standard signal processors (like heavy compression, auto-tune, artificial reverb and delay, etc) don’t really have a home in binaural recording (no hard feelings, Akon).
Second, the hey-days of the pop music industry were built on radio airplay – when most listeners played their music through speakers, and heavy compression became crucial to make that new hit single stand out from the rest.
The real strengths of binaural recording are in either capturing sound exactly the way we would hear it in a live setting (perfect for live-recorded concerts), or as an immersive special effect (ever heard a drum set from above your head?). It’s perfect for the you-are-there intimacy of acoustic folk, jazz and classical, as well as creating incredible sonic landscapes where instruments and sounds are coming at you from all directions, swirling around your head!
And good news: companies like Halifax’s Kall Binaural Audio are now making it easy for you to add your next album to the list of ground-breaking and truly unique recordings out there!
For more info, and to hear the 3D binaural difference for yourself, grab your headphones and check out www.kallbinauralaudio.com
ALEX KALL is the Stage Manager and Marketing Coordinator for Symphony Nova Scotia. He also owns and operates Nova Scotia’s first and only dedicated 3D recording service, Kall Binaural Audio.