Hi, I’m John Calder of Acoustic Geometry When we talk about acoustics we should talk about your brain on sound because our sense of hearing, ears and brain, are sensitive to acoustics. And hearing, is a survival tool. You’re hunting for lunch 30,000 years ago You hear a twig snap. (snap) If your brain doesn’t tell you instantly which direction to run, you might be lunch. We’re always listening for potential danger. Short, sharp sounds called transients, like twig snaps (snap) Are mostly what we listen for. Transients help your brain create a picture, a sound image, of what, where, and how big by comparing timing, loudness, and tone differences between ears. Your brain knows whether its (big growl) or (small meow) With a pair of microphones recording a symphony, or me talking, we record the timing, loudness, and tone differences between mics. stereophonically, for accurate sound image playback. Our brains are happiest when we hear accurate sound images played back with electronic speakers and acoustics that don’t damage timing, loudness, and tone. Also known as phase, amplitude, and harmonics. Here’s big point #1 Good room acoustics are essential for accurate sound imaging. In our video “How Sound Works (In Rooms)” we show that flat surface reflections damage timing, loudness, and tone and create the need for acoustic treatments. But some acoustic treatments are part of the problem. Because they also damage timing, loudness, and tone. That includes absorbers. Too many absorbers can kill the sound energy in your room, your ambiance. Too much absorption creates a mismatch with what our brains expect to hear. And it diminishes our pitch perception. That leaves us with the other room treatment. Diffusors. Which don’t kill ambiance or pitch perception. But there is a problem. Phase-shift diffusors like quadratic residue designs work by distorting the timing or phase relationships within the reflections And that will damage the sound image. That’s a problem because it messes with the twig snap. (snap) Our brains are far more sensitive to phase than frequency for sound location. It’s a suvival tool. Here’s big point #2. Timing accuracy called phased coherence is essential for recording and hearing accurate sound images. Can we use common sense to improve our sense of hearing? Sure. Use acoustic treatments that preserve timing, loudness, and tone relationships. Fortunately, there is an acoustic treatment that preserves them. Phase-coherent diffusion. By the way, this isn’t new science. RCA Studios used phase-coherent diffusion back in the 1940’s. Phase-coherent diffusors smoothly spread out reflections, reducing hot spots, and allowing us to use less absorption. This improves our hearing. It’s the way our brains work. Our brains are really amazing. Capable of hearing location, size, and type of sound almost instantly given the right acoustics. Treat your room with Acoustic Geometry Curve Diffusors Your brain will be happier. Thanks for watching.