Headphone listening has become very popular as people consume radio, TV and music out and about. For this reason, researchers and companies are starting to revisit binaural technologies. For example, you can read this BBC R&D blog about their experiments with binaural.
One of the strange things about listening to a favourite stereo track on headphones, is that the musicians appears to be giving the concert from between your ears. Binaural reproduction is meant to overcome this by reproducing at the ears the exact sound waves that you would hear if you were listening to a band playing normally, say at a gig.
Binaural recordings are made by placing two microphones at the entrance to the ear canal. You can either use your own head and special microphones (I have a pair of these from Roland) or you can use a special mannequin (a dummy head) with microphones buried into the side.
There are several technical reasons why binaural recording have not become commonplace, one of which is that binaural often does no better than a standard stereo recording at getting the band out of your head. Everyone’s head is a different shape and size, so unless your head is similar to the one used for the recording, your brain doesn’t externalise the sound. Another failing is that as you move your head around, the aural world swivels around with you. This unnatural effect is another reason for sounds appearing to be inside the head. The solution to this is to use head tracking, changing what is sent to the headphones based on which way the person is facing. In the main photograph, the tracking is being done by the infrared cameras on the tripods. I heard the system at the second BBC Audio Research Partnership event, and it was the most impressive binaural system I’ve heard.
Now there are consumer devices that can track listener movements such as Kinect or the accelerometer and gyroscopes in Google Glass, maybe we are getting to the point where binaural might go from being a great research tool to an everyday audio format.
Want to get a sense of a simpler binaural system? Grab some headphones, close your eyes and try this classic demo:
 Photo: www.gregharding.co.uk