Adventures in 3D Sound: Bach and Binaural Recording

Edgar Choueiri’s digital audio filter can take almost any recording and turn it into 3D — stereo tracks take on new depth and sound amazingly realistic after a quick pass through his algorithm.

But the only way to experience perfectly realistic 3D audio is by listening to a binaurally recorded track. Binaural recording follows the same principle as a 3D camera, which simultaneously captures a scene from two slightly different vantage points — one from the perspective of each of your eyes. Instead of two camera lenses, binaural recording uses two microphones inside the ear canals of a dummy head. At Princeton University’s 3D Audio and Applied Acoustics Lab, Choueiri has two dummy heads: one from the German company Neumann (famous for its high-quality microphones) which he calls Fritz, and another from Denmark named Lars.

A binaural recording captures sound exactly as you would hear it live, through just two channels. When Kurt Andersen visited Choueiri’s lab, he made a binaural recording using Fritz, which was later processed for perfect 3D realism by Choueiri’s filter.

Video: A First Listen to 3D Sound

Choueiri has also applied his algorithm to existing stereo recordings. You can experience Bach’s Mass in B minor in full 3D glory below — plus, to hear exactly how the algorithm changes the sound, we’ve posted a section in which Choueiri’s filter switches on and off.

Audio: Mass in B minor, Cum Sancto Spiritu, Johann Sebastian Bach (3D for speakers)

Audio: Mass in B minor, Cum Sancto Spiritu, Johann Sebastian Bach (3D filter on/off)

As you listen, the sound image you’ll hear won’t be quite the same as being in a hall with the performers. That’s because in stereo recordings like this one, the instruments and voices have been recorded with lots of different microphones and then placed in your left and right ears (using panning) by the person who mixed that recording. Because of crosstalk (when sounds intended for your right ear end up in your left ear, and vice versa), that placement ends up sounding less precise to the ear — in other words, if the sound was a picture, the crosstalk makes it fuzzy. Choueiri’s algorithm eliminates that effect, and lets you experience the acoustic space exactly as that audio engineer reconstructed it — it sharpens the image and gives it added depth and texture. It’s still not real life, but it sounds pretty darn close.