Live or dead?

In yesterday's post, inspired by a great Ask Paul question from Mike in Pasadena, I offered an easy room dimension calculator. Getting these dimensions close is a huge step in the right direction of achieving good sound. Unfortunately, most of us don't have the luxury of a dedicated room so we have to work within the constraints afforded us. Whatever size room you wind up with there will still be additional steps required to optimize performance. For example, in Music Room One we have added several basic tweaks, like eliminating the corners. You can see how we did this by reviewing the third video in our series, Building a new Music Room. These corner angles are very helpful. They eliminate the tendency of sound build up in the corners, act like a partial horn (as you see in concert halls), and in our case, Helmholtz Resonators (though as resonators they were a failure). Once built, there remained a small slap echo which we reduced by covering up the remaining corners where the ceiling meets the walls. This took little more than some fancy molding. You can see how we did that in this follow-up video. Once the basic structure has been implemented the next decision is how lively to keep the room. By 'live' we really mean reflections. Sound reflects off hard surfaces—the difference between inside with walls vs. outside with none. What you hope to achieve is the perfect blend of live and dead: reflective and absorptive. You know it's right when your voice sounds natural within the room—which begs the question, how do you measure that? I find the most effective tool for determining if a room has the right balance of live or dead is my ears. I can walk into a room and get a pretty good feel how it will perform with speakers. You can as well. Empty the room of objects and pay attention to your voice as you walk around. If it sounds like you're in a reverberant fishbowl you'll need some absorption to damp those reflections. And the opposite is true. Stick your head out of your home's back door and say a few words. Note how the lack of walls sucks the life from your voice? If your voice sounds the same in your room, it's over damped. Tomorrow we'll look at remedies for over/under damping.