After talking to Prof Arnold Starr, acclaimed expert in neuro accoustics about how the human brain localizes sound it became clear to me that any recording device and environment that were to give our auditory cortex the ability to generate a precise illusion of the position of a sound in a three dimensional space must contain all the cues the system needs and dwells on in real life. The conclusion was quite simple: the recording device must reasonably reflect the human hearing apparatus, ear separation, ear canal, pinna, ear lobes and all. It must be a human head.
So I went out to talk to someone who operates exactly such recording device: Dr. David Chesky with Chesky Records and their boutique label HDTracks who almost obsessively creates recordings using binaural technology that have as their center piece an artificial human head harboring precision point microphones at excatcly the same location where we have our ear drums. I did this not only from the passion for our trade and my almost childlike curiosity, but with one question in mind: Why do our loudspeakers get such great reviews on stereo imaging even by people like Steve Guttenberg who have surely seen and heard it all. And then, what can we do to get better. Here is what I found out.
Kvart & Bølge: how did you get involved in recording music in a way that provides a particularly precise stereo image.
David Chesky: I was a conductor so I had the best seat in the house. The orchestra always sounded great when I was conducting for TV and film and I thought, it would be great to put a mic here so people can hear what I hear.
K&B: Can you explain what a binaural recording is and what it takes to produce one?
DC: Binaural is when you record with a Dummy head that is calibrated to hear how a human hears. It works by getting the 3D pinna cues that you have in the human ear. When decoded or played over headphones it is very immersive and 3D.
K&B: can you explain the process of how you work and how it can be explained that your work stands out amongst so many highly professional recording studios?
DC: I can sum it up in one word, simplicity. The best single point mic (in this case Binaural dummy head) great speaker cable’s into an A/D converter and that is it. No post EQ, no compression or anything to degrade the music.
K&B: That sounds almost like our concept for building speakers. Straight high quality wires from the amplifiers, no cross overs, no electronics, its what Bjørn Johannesen calls "organic sound with no additives". Now: how is it possible that Chesky records can produce binaural recordings that provide immersive sound not only on head phones but also on loudspeakers?
DC: We add a customized diffused EQ filter to the binaural recording so it can decode to speakers or headphones. It is something we have been working on for awhile.
K&B: I have been listening to many of your binaural plus recordings on speakers and must say the results are actualy pretty amazing. What are the attributes a loudspeaker should have to produce a binaural recording accurately?
DC: the more directive the speaker the better it will be.
So there it was: Directiveness or directivity as its also called was the holy grail of stereo imaging. But what causes a loudspeaker to be directive? Well horn speakers are naturals at "funelling" sound into one direction, but for those who don´t want a large horn in their living rooms the another great way is a full range driver system. And a small full range driver to be precise. Size matters in the context of directivity, a small size prevents a phenomenon called "baffle step diffraction" by which sound of wavelengths greater than the cabinet width bounces back into all directions diminishing directivity. And so I had my answer: since our SoundSommeliers with their sleek front that is made possible through the quarter wave bass extension directiveness falls in their nature. And with it comes the stereo imaging that Steve Guttenberg spoke so kindly of.
So the question that remains: Can it still be improved? A question for Bjørn. More on here later.