The Final Component in Your System is... Your Room

We generally think of the speakers in our stereo or home theater systems as the final link in the audio chain — and the one that makes the biggest difference to our ears. But it's really not that simple. There's much more to the sound we hear than just what comes out of our speakers.

In addition to the sound from your speakers, you hear reflected sound from your room's four walls (above left). Your room's ceiling and floor contribute reflected sound, as well (above right).

The sound that you hear in any room is a combination of the direct sound that travels straight from your speakers to your ears, and the indirect reflected sound — the sound from your speakers that bounces off the walls, floor, ceiling or furniture before it reaches your ears.

Reflected sounds can be both good and bad. The good part is that they make music and speech (like movie dialogue) sound much fuller and louder than they would otherwise. (If you've ever played your speakers outdoors where there are no walls to add reflections, you've probably noticed that they don't sound very good — thin and dull, with very little bass.) Reflected sound can also add a pleasant spaciousness.

The bad part is that these reflections distort sound in a room by making certain notes sound louder while canceling out others. The result may be midrange and treble that's too bright and harsh or echoey, or bass notes that are boomy, with a muddy "one-note" quality that drowns out deep bass.

Because these reflections arrive at your ears at different times than the sound from your speakers, the three-dimensional "soundstage" created by your speakers and the images of the instruments and singers may become vague or smeared.

Sound energy is in the form of invisible waves. Since our hearing can perceive sounds from 20-20,000 Hz, we're talking about wavelengths that range from 11/16" at 20,000 Hz, to over 56 feet at 20 Hz.

These same reflections affect the music's timbre, or tonal quality. For example, a flute and an oboe have different timbre; they should sound different even when playing the same note, because each instrument's tones have a different harmonic structure. Reflections can obscure those crucial differences.

So, for all of these reasons it should be clear that your room is really the final component in your system. As with any other component, there are steps you can take to improve your room's performance. Many people find that after accomplishing as much as they can with speaker placement, they still aren't happy with their system's sound. If you feel that the way your room interacts with your speakers is causing problems, it's time to turn to Science; the science of acoustics, or more specifically, room acoustics.

The ABCs of room acoustics:
Reflection, Absorption, Diffusion

As we talk about room acoustics problems and room treatment solutions, the three main concepts we'll keep coming back to are reflection, absorption and diffusion. Some reflected sound is necessary for music and speech to sound natural, but too much can rob your system of sound quality. You can control reflected sound by absorbing or by diffusing (scattering) these reflections.

Treating room problems can be simple, like installing drapes over a large expanse of glass, or placing an area rug on the floor between your speakers and where you sit to listen. Or you can treat your room's trouble spots with specially designed products that change the way your room responds to sound. But the first step is understanding the basic concepts of room acoustics and the part they play in your everyday listening.