Beautiful music

Yes, beautiful music is possible even from a "cheap" sound system. Many readers just can’t believe that the place where you listen to music plays a significant role in determining how sound frequencies can be reined in to reproduce to-die-for music. In our last column, we featured the music room of Binondo businessman Vicente Lim, and how he was able to maximize the size of his room (no more than 20 square meters) to get the kind of music he was aiming for.

The problem at the moment is that there are only a few room acoustic materials available on the market and, more often than not they do not conform to the right specifications. Perhaps we should take the cue from Vic who did his own research on how it could be done right. There are tons of reading resources on the Internet about room acoustic treatment, and some even provide exact specs on how to go about it. For AudioFile readers, Vic has volunteered to help those interested (e-mail me to get Vic’s contact numbers).

The first step is to understand how sound waves behave inside a fully treated room. For the experience, you may want to visit the showroom of Audio Amplified, an audio equipment dealer along C-5 in Libis, right across Shopwise. This dealer has spent time and money to showcase what a music room ought to be.

Reproducing good music in symmetrical rooms (those built like shoe boxes) is easier than in asymmetrical ones (rooms that have unequal wall lengths). In asymmetrical rooms, sounds are reflected many times over before they reach our ears. Listening nuances such as peaks (those piercing high frequencies) and distortions are caused mainly by unregulated sound reflections.

Fortunately, sound reflections in a room can be controlled. When handled correctly, these reflections can make a lot of difference even if you own an inexpensive sound system. Untreated rooms produce "muddy" sounds while rooms that underwent acoustic corrections can give you sounds that are clear and tight.

There are two, albeit unconnected, aspects of acoustic treatment that we can use: One is sound isolation. With this, we try to minimize the seepage between rooms, and between the inside and outside of a room. The other, which is what this column is all about, is treating the room itself to lessen reflections that give life to reverb, echoes and standing waves.

Go into an empty room and clap your hands. Listen closely, and you’ll hear a series of intimately spaced echoes. With these echoes come recognizable musical pitches, called ringing, particularly if the room is small. Sound striking the walls is what produces these echoes. Aside from this conspicuous interference, the ringing also causes certain frequencies to be emphasized.

To eliminate most reflections, deadening the room — with commercial acoustic foam, fiberglass or heavy blankets (as absorbers) — often does the trick. These materials are useful for absorbing mid-range and high-frequency reflection; however, they do nothing to control low-frequency reflection.

Low-frequency reflection is best treated with resonating boxes designed specifically to absorb low-frequency energy. Called the bass traps, they absorb low frequencies that fiberglass and foam rubber are unable to. The bass traps are made of plywood panels, and designed to vibrate over a broad range of bass frequencies. Fiberglass is mounted behind the panels to dampen the vibration. The process absorbs low-frequency energy from the room.

Bass frequencies spawn standing waves when they bounce around in a room. Standing waves are actually pressure nodes that are fashioned when a sound wave reflected from a wall crashes directly with the sound emanating from the loudspeaker. At some point, the reflections underpin the direct sound, increasing the level at that particular spot in the room. On other occasions, the reflections are likely to cancel the direct sound, bringing the volume down or, in some cases, eliminating it altogether. Bass traps make sure that this never happens.

* * *

For comments and suggestions, e-mail me at vphl@hotmail.com.