First reflections matter most.
When sound leaves your speakers, some of it travels straight to your ears—that's the direct sound, the one that carries the music's essential information. But sound waves also bounce off your side walls, floor, and ceiling before reaching you. These first reflections arrive just milliseconds after the direct sound, too quickly for your brain to separate them. Instead, your brain blends them together, and that's where problems start.
First reflections blur imaging. They smear the precise locations of instruments in the soundstage. They can alter tonal balance, often adding brightness or harshness. In badly treated rooms, they can even create a sense that sound is coming from the walls rather than from the space behind the speakers.
Finding first reflection points is simple and requires only a small mirror and a patient friend. Sit in your listening position while your assistant holds the mirror flat against the side wall, positioned halfway between you and the speaker. Have them slide the mirror forward and back until you can see the speaker's tweeter reflected in it. Mark that spot. That's where sound from your speaker first hits the wall before bouncing to your ears.
Once you've found these spots on both side walls, you have options. You can absorb the reflection with a soft panel or heavy drape. You can diffuse it with a bookshelf or specialized diffuser. Or you can do nothing if your room already sounds good. Some speakers and some rooms work together perfectly without treatment.
The key is knowing where the problem areas are so you can address them intelligently.
