The other weekend, I was fortunate enough to be given a demo of Smyth Research's fabulous Realiser A8 headphone processor, which, when properly implemented, allows for a truly transformative multi-channel listening experience from headphones. I have a full review of the A8 and the entire Smyth system coming soon, but the experience got me thinking, "How did they do that?" Smyth employs what they refer to as HRTF or Head Related Transfer Function, which refers to the way in which our brains hear sound as a result of our heads, shoulders, knees and toes. Okay maybe not knees or toes, but our shoulders, heads and ears definitely play a role. Smyth takes things further than most by incorporating the listening space itself into their measurements, though the basic concept stems from binaural recordings.
Looking into the topic of binaural recording techniques and info, I stumbled across the website for Princeton (yes, the university). Deep within the catacombs of the Princeton site rests a series of pages labeled 3D3A, the name given to Professor Choueiri's spatial hearing laboratory where he, along with his colleagues, have developed a filter to more effectively eliminate crosstalk present in traditional stereo recordings. The technology, branded DynaSonix, utilizes a filter pack called BACCH that factors in the dimension of the human head and uses those figures to create a buffer of sorts to ensure a crosstalk-less stereo listening experience. The resulting sound is far more three-dimensional, due to your right and left ear being able to hear sound that is more directed at them, as opposed to having to sort through sound waves that arrive at both ears, albeit at slightly different times, frequencies or levels. In other words, it eliminates crosstalk. Stereo imaging is still preserved, but certain audible elements in a mix can now be directed at either the right or left ear, or they can be made to play off each other with more precision, resulting in the surround sound effect. There are a few demos on 3D3A's website, which have been mixed to be played back via your laptop's internal loudspeakers. You can watch the video below and listen for yourself.
Professor Choueiri's technology has some interesting application possibilities. For instance, if properly employed, you could effectively achieve near or surround sound performance from a two-channel soundbar. The close proximity of many soundbars' "left and right" speakers is almost ideal to extract the most from Choueiri's binaural tech and crosstalk filters. Virtual surround sound performance from built-in HDTV speakers is another area that could benefit from the Choueiri's filter. On the flip side, there are many commercial and business applications as well, some of which Choueiri alludes to on his website, including solutions for teleconferencing and even hearing aids. One thing is for certain: the technology works, as demonstrated in the video above and, when properly implemented, it has the potential to take your two-channel listening experience to new heights - I mean dimensions.