A history of Omniwave

I believe that Omniwave, "the inaudible loudspeaker", is the most profound development in sound reproduction since stereophony.

What Omniwave does is reveal the original spatial information of a recording by diffusing its own acoustic signature. It doesn't add artificial effects like Dolby Atmos Music; instead, it avoids the masking effects introduced by traditional loudspeakers. The result is a stunningly realistic immersive experience.

Omniwave is the life's work of Leo de Klerk, who started his career as a pianist and composer and later became a recording producer. At the time of his invention, Leo and I were working together as producers in our partnership firm, Bloomline Coryphée. I thus had a front-row seat on the road to his invention.

The problem that Leo initially set out to solve was “sweet spot fatigue”. We spent many long hours editing recordings in our control room, but to hear a convincing stereophonic image we had to keep our heads fixed in one exact spot between the loudspeakers, the “sweet spot”. Move even an inch to the left or right and the stereophonic “image” would start to break down. It was very unpleasant to sit completely still for hours on end, editing our way through a recording with our “head above the dot”, as Leo called it.

“Wouldn't it be nice,” said Leo, “to try and get rid of that sweet spot?” That made me laugh, because the only way to do that was to turn off the amplifier.

But Leo was onto something. We already knew that human hearing found the loudspeaker itself “interesting”. Something about a loudspeaker made it sound like a loudspeaker. Whatever you played back on it sounded as if it was locked up in that little box. Could we somehow make the sound break free from the enclosure?

We knew that the problem had something to do with localization. And we had learned in college that humans localize a sound source by detecting differences in sound pressure and arrival time between our two ears. If a sound source is to our right, the sound will reach our right ear earlier and with a higher sound pressure than our left ear. The brain then tells us: "oh, this is coming from the right".

But our hearing is far more sophisticated than that. Leo realized that we can identify the shape and location of a sound source by how its radiation pattern interacts with our head and our pinna — the visible part of the ear. The pinna's ridges and folds reflect and absorb sound differently depending on the direction from which the sound arrives. This causes coloration — a property that you can't consciously hear, but that our hearing translates into location cues. It is as if every direction is “color-coded” to help us determine the source's shape and location. Leo called this the “shape-related transfer function”, extending the familiar concept of the “head-related transfer function” to include the characteristics of the sound source.

This made the problem clear. A traditional loudspeaker's shape and a location provide our hearing with localization cues that apparently get in the way of the spatial information of the recording (hence the recording sounding like it is "boxed in"). The challenge was to remove the loudspeaker's localization cues without affecting the original recording.

Now the only way to do that would be to diffuse the acoustic signature of the speaker without diffusing the reproduced sound. Easier said than done! It’s easy to diffuse both: just play back through speakers 20 meters away in a cathedral. But of course that's not what we want. We want to hear the recording in full detail, not some fuzzy representation of it.

In order to become diffuse as a sound source, the loudspeaker would need a radiation pattern resembling a plane wave: a sound field that our hearing would interpret as coming from afar.

Now this was all great in theory, but what would that loudspeaker even look like? I couldn't envision it at all, and honestly thought it could not be realized. But Leo was not the kind of person to give up that easily. He went on looking for a solution, tirelessly, for months on end.

One day, Leo called me and said, “Come over. You should hear this.” I came to the studio and saw a configuration of two microphone stands, each holding one speaker near the floor and one at around 7 feet high. No speakers at the back. Then Leo started the CD-player.

It was one of our own recordings, with the Netherlands Wind Ensemble playing in The Hague's New Church. I was shocked, but not because I heard something new. I had heard the same thing before: at the venue of the actual performance. But what took my breath away was that I could even walk around in the control room as if I was walking around on the stage. The sweet spot was gone.

Feverishly, I went through our catalogue of recordings. My recording of the Müller organ in St Bavo's in Haarlem — there it was, above the speakers. Apparently, the floor reflections, no longer masked, were making that happen. Then a recording made in a park with an artificial head: birds everywhere — left, right, up, down, even behind us. A small aeroplane flying overhead. Then we played a monaural recording of a jazz trio. Something wasn't right — it didn't sound like mono at all. We realized that the spatial cues in the recording were faithfully revealing the studio acoustics, making it sound almost fully stereophonic.

Yes, Leo had been onto something. Although that now seemed like the understatement of the century.

The road from prototype to patent and the “Omnidrive” manufactured product was a long one. The challenge in patenting the invention was that its working principle went multiple steps beyond the prior art. The patent had to explain a concept of human hearing that was not readily accepted in audio engineering circles. (Amusingly, an engineer attending one of Leo's demos in Germany got really upset and told us that “this cannot possibly work”, while admitting that he had just heard that it did.) Another challenge was developing the drivers and other components needed to accurately produce the required radiation patterns.

But eventually, Omniwave was successfully launched, making its way into major events and locations like Google I/O, the Netherlands Houses of Parliament, and the Philharmonie in Berlin.

In 2020, Leo left us, way too soon. But that he was able to see his invention break through has been a consolation to his loved ones and friends.

Leo was an exceptional human being, whose genius cannot be replaced. But his spirit lives on in Omniwave, a great gift to music lovers all over the world.