SIGNALS

Let's see a show of hands. How many of you often listen through headphones? Thanks to that camera looking back at you from your device, and some pretty cool software I got from a guy in Russia, I can see that many of you do indeed listen through headphones. You can put your hands down. My question then, is why aren't you listening to binaural recordings?

Binaural is often confused with stereo, but they are quite different. All binaural recordings are stereo, but almost no stereo recordings are binaural. Binaural, then, is a special kind of stereo. Stereo can be encoded in any number of ways and played back over two loudspeakers or headphones. Sure, you get phantom images and all that, but it's an entirely artificial and unnatural way of recording and playing sound.

In contrast, binaural is a recording technique that replicates the way we naturally hear sounds. In particular, we have two ears facing in opposite directions placed on either side of a head. That physical arrangement leads to a very specific encoding of sounds. For example, the ears are spaced a distance apart, and the head casts a frequency-dependent acoustic shadow so that, for example, sounds from one side arrive later at the far ear and have a rolled-off frequency response at that ear. While it seems complicated, it is how we naturally hear sounds.

The best way to make a binaural recording is with a dummy head, which looks like a human head and has probably freaked out more TSA baggage inspectors than all other microphones combined. The dummy head is the size of a human head, complete with nose and ears. Critically, the microphones are placed where your eardrums would be. The two output signals, one from each ear, are recorded to two tracks. The dummy head does all the encoding, naturally. There are other ways to make a binaural recording, but the dummy head is the classic way, and probably the best.

To play back a binaural recording, you have to put the speakers back to where the microphones were. That is...wear headphones. The result is a remarkable "you are there" experience

To play back a binaural recording, you have to put the speakers back to where the microphones were. That is, you need to wear headphones. The result is a remarkable "you are there" experience. Now, I'm sure you already know all this, and have listened to your fair share of binaural demo recordings—things like rain, or crickets or someone cutting your hair. Competent but boring.

For something more lively, check out this binaural recording made by 19Bozzy92. Wait! Stop! Put on headphones first! Now, that demonic binaural screaming you hear is the sound of some Ferrari Formula 1 cars turning practice laps at the Mugello Circuit in Tuscany. Il Suono della Ferrari. Si agita il sangue.

So why aren't you listening to binaural more often? Because there are very few binaural recordings. Most soundtracks are in regular stereo, mixed in the studio from multiple tracks. The sonic ingredients are spatially artificial to begin with, and so the stereo playback is too. That's really too bad; given the number of people listening to music and movies over headphones, and all the hype about VR, I wish companies made more of an attempt to give us the realism of binaural playback.

Oh—that quip about me spying on you—I was just kidding. But you do have a piece of tape over that thing, right?