How does BACCH Sound?

BACCH: The Stereo Purifier.

Stereo comes from Greek, meaning "related to space", and is used in reference to the three-dimensional reality we live in. Yet stereo sound vastly underdelivers on its name. This is why BACCH was originally coined a “stereo purifier”— you’re hearing perfect stereo sound.

What does BACCH sound like?

Real life. Like the true 3-dimensional sound that you experience every day.

Let us explain.

At it’s core, a BACCH filter cancels out your ability to hear your speaker locations. So, imagine a stereo setup: there’s a left speaker, a right speaker, and between those two speakers you get a phantom center along with an entire stereo span. All of the instruments, the voice, the reverb, the room, etc., are all within that stereo span — the line between two speakers. Are they meant to be? Or is that just the fact of the matter?

When stereo was invented, it was meant to be the end-all in audio. We have two ears, so we just need two speakers, right? Unfortunately for us, our brains need more convincing than that.

Now, let’s imagine if we could expand that stereo span from a line to maybe an entire circle of sound reaching around you. Imagine a guitar that was at the right speaker moving beyond the speaker into space, closer to you, still on the right side, but a foot or two from your ear. The keyboard that was at the left speaker is now noticeably out at 90 degrees to your left. The voice is still perfectly in front of you, but maybe it’s a bit closer? And it’s a bit less… cluttered? The percussion perhaps didn’t move to the left or right, but actually feels more accurately deeper in the room beyond the speakers. Interesting. And finally, that enveloping reverb, that room tone, that ambience… it’s like you’re there. You almost don’t notice it because it feels so… natural? The sound of the room in the recording is all around you, just like your real room is.

That’s when you realize you’ve had a BACCH filter on. You turn it off, and everything snaps back to that line between the speakers. The keys and guitar both are sucked back to your right and left speakers, the drums feel flat, the voice is cluttered, and perhaps the most devastating… the room is gone. That ambience and reverb that wrapped around you like a blanket has vanished. You can still hear it, but you don’t feel it. It’s sterile. You’ve been pulled out of the room and are just listening from the doorway. That’s a shame.

A BACCH filter sounds like real life because your brain is recreating the reality of that recording. Your brain is too smart to be fooled by loudspeakers, no matter how incredible the speakers are and no matter how perfect the recording and mix is. But once you can remove the speaker locations from the recording? Your brain takes all of those cues present in the music and places them accurately around you. That’s why BACCH is so incredible: there’s no upmixing or remastering, no change to the source content. In many ways, you’re just hearing it more accurately. In many ways, BACCH is what stereo was meant to be.

The proof is in the pudding.

Obviously we can’t give you a demo via this wall of text, but we can describe one particular situation that no other demo or technology can accomplish (and ours can):

One of our demos over speakers is as follows: we place microphones in the ears of the listener, and simply record one of us walking around, making noise. Anything that happens in the room around the listener is recorded by those binaural mics, exactly how they would hear it.

Now, what happens when we play that recording back? Over headphones, because it’s their own binaural recording, it sounds extremely accurate.

But over speakers? It’s trapped in the stereo span, just like any other audio would be.

Now what happens when we turn on the BACCH filter? The listener now perceives the previous recording as if it’s happening all over again, in real time. The sound isn’t just randomly pushed outwards or around the listener, it is perfectly accurately reproduced in the space around them. If we knocked on the door behind them, they hear a knock on that door. If we whispered in their ear, they hear a whisper in their ear. If we clapped our hands at 90º to the left of the listener, the clap is right there. It is uncanny, and all over two regular speakers placed on a desk in front of them in a normal stereo configuration. That is the power of the BACCH filter, wrapped into one quick demo.

What about Headphones?

Great question. Technically, headphones do what a BACCH filter is doing - you’re getting sound directly from “speakers” to your ears. All those cues are perfectly delivered. So why don’t headphones create a 3D image all around us? Unfortunately our brains are yet again too perceptive.

Headphones can be a wonderful, immersive experience and some headphones have quite a large soundstage. Binaural audio was made for headphones (and BACCH enabled speakers). But unless you are listening to a true binaural recording that matches your own physiology, such as described in the demo above, that sound will never actually sound much outside of your head. You’re getting all the cues from the music, but they’re so dry and direct that it’s unrealistic to real life. For example, in real life, your left ear will always be able to hear what your right ear is hearing, albeit much quieter. With headphones, that’s not the case unless it’s mixed or recorded that way, and when it’s mixed that way, the sound still just ends up falling somewhere between your ears, in your head, or maybe just in front of your face.

That’s why BACCH has yet another solution just for headphones — our headphone filter. We perfectly recreate the sound of any pair of speakers in front of the listener, then apply our 3D BACCH filter on top of that. The speaker recreation works for nearly 100% of people because we have fairly universal physiology directly in front of us for perceiving sound. The result is wonderful externalization of a complete 3D soundstage. This means that all audio realistically sounds outside of the head in a proper soundstage, and the user can rotate their head within that image. On top of that, all binaural and spatial imaging is retained due to the nature of our 3D filter. It’s a truly elegant solution that you have to hear to believe.