Add Dimension to Your Tracks with the âHaas Solo Effect" Here's how to make your mono-tracked guitar solosâand moreâsound larger than life. Welcome back to the Dojo! This month I'm going to explain the Haas effect and how to use it on exposed parts (like your solo) and get it sounding wider than your speakers! I call it the "Haas Solo Effect"âa pun in tribute to my lifelong love of Star Wars. Tighten up your belts, we're going to throw around galactic-size audio. The Dojo is now open. In 1949, Dr. Helmut Haas discovered a curious psychoacoustic phenomenon based on how our brains perceive the directionality of sound (also known as the "precedence effect"). This is based on what acousticians call HRTF (head-related transfer function), and it has everything to do with the time it takes for a sound wave to reach one ear and then the other ear that is the furthest away from the sound source. The longer the time, the more "hard panned" the sound becomes.