Truth be told when I invited Bjørn Johannesen into starting a company to build loudspeakers around his acoustic concept that had been acclaimed in the DIY world for many years now, but was never made available commerically for those who didn´t want to get out plywood and set screws, the one thing that is really making us successful now wasn´t even on my menu at the time I commited to the project: Stereo imaging. When later Steve Guttenberg´s review came out on CNET and he immediately picked up on our speakers ability to provide an immersive stereo image, it actually came to bug me a little that apparently I simply got lucky. So I decided to go deeper and catch up on the concept of immersive sound and decided to talk to the two people I judge to know more about sound localization than anyone else I can think of: Dr. David Chesky with Chesky Records and HD tracks, expert and pioneer in the field of binaural recordings and Prof. Arnold Starr professor emeritus at the University of California, Irivine and for many years a leading expert into how the human ear and brain processes sound.
I figured, you see, that there are really three components to the experience of a truly three-dimensional soundscape. First we understand how our ear and brain creates an acoustic representation of the world we live in. Second to understand how a soundscape can be recorded and digitized in a way that it contains all the information our ears and brain needs to put things in their place. And lastly how to get it out of the digital realm and back into our ears to have it sound as it did when it first happened.
When talking to Prof. Starr, I quickly realized that the topic of sound localization is incredibly complex and our brain highly sophisticated. Needless to say there has been an evolutionary advantage to hearing both pray and predators with precision and this advantage has created a highly honed apparatus consisting of earlobes, ear canals, ear drums, sensory nerves and an auditory cortex that processes minute cues about the origin of sound in space that that is truly remarkable in its precision.
Prof. Starr talked to me about group and phase delays of sound, the miniscule difference in time and rise and fall of a sound wave that the brain uses to give us an acurate idea of where the origin of this sound might be. The increasing importance of interaural differences in levels as frequencies increase and monaural cues from where the outer ear acts as a filter to provide us with an idea if a sound might come from in front of us or from behind, and to some lesser degree from above or below. My head started to spin.
But what became clear from this conversation was that for the human brain to create a congruent sound scape, it was indispensible that all these minute cues would already be present in a recording.
And this is exactly what Dr. Chesky and his boutique label HD Tracks by Chesky Records are doing. Mimicking the human hearing apparatus closely by placing the microphones inside an artificial head, lobes, ear canal and all, their unique binaural plus series of recordings produces music in high resolution that provides truly immersive three-dimensional sound from not only headphones but also speakers.
Most recording studios, even very good ones, you see, rely on a very limited subset of such cues. Instruments are recorded in sound proof chambers, and the listener is only granted a limited idea of where the recording technician would like for him to perceive any instrument in his or her listening experience by increasing the sound level of that instrument of one channel compared to the other. No phase delay, no change in onset, no interaural differences, other than sound pressure.
This is what makes the work of Dr. Chesky, so remarkable; A Jazz pianist, conductor and composer by trade, he has been relentless for many years in his pursuit immersing the listeners of his company’s recordings in a space that is precise and congruent in all three dimensions and time.
By placing microphones in an environment that closesly resembles a human head all cues the human brain requires to localize sound are actually included in the recording. And by using what they call Binaural Plus technology, this not only works when played on headphones, but also when played on speakers. Especially speakers that are capable of precise stereo imaging. Here is a brief explanation of how it works:
The results are truly stunning: Instruments and vocalists position themselves in space, creating an almost holographic experience that sounds so much like will have when it first happened. And then as I sunk deeper into these soundscapes, I entered a deeper sense of relaxation and immersion than my heady self is usually capable of. When later contemplating this experience it dawned to me that an acoustic environment that makes sense and is completely congruent, can put our ancient pray / predator brains to rest and into trance because we don’t have to scan our accustic reality for things that might be pray or pray on us. And this state of congruence is a state where a musical experience becomes truly meaningful.
So it was only natural that I would go and interview the man himself and get some insight into how to build better loudspeakers to make best use of this amazing material. More on this soon...