In the beginning, there was perfect sound. Then man invented rooms and forever made it difficult to achieve good
sound. The end? Luckily, no. Sound waves emanate out from their sources and strike room boundaries in predictable
ways. Since tons of studies have shown that reflected sound is inherently inaccurate sound, controlling reflected
sound is the key to making our spaces sound "good." While it's true that we all may have our own ideas as to what's
a "bad" mixer, a "bad" loudspeaker or a "bad" microphone, I'm sure we can all agree on what a bad-sounding room
sounds like. Two common examples of bad-sounding rooms that you're probably familiar with are gymnasiums and tiled
bathrooms. The good news is that by implementing the proper acoustical treatments, we can make even the
worst-sounding room good enough to yield world-class sound. Controlling reflections yields truer sound and allows
the "real" sound of an instrument, voice or loudspeaker to come through. The two methods of controlling sound are
sound absorption and sound diffusion.
Hard room surfaces are responsible for the most detrimental reflections like standing waves, flutter echoes and
frequency room modes. Ever clapped your hands and heard a ringing, repeating, hollow sound? Say hello to your arch
rival, Mr. Flutter Echo. Ever been in a conversation with someone or played music in a room where the low
frequencies were overpowering the rest of the sound, making for poor intelligibility? Meet Mr. Room Mode and his
nasty sidekick, Low End Buildup. The three types of sound wave reflection are called axial, tangential and oblique
modes, which relate to which direction in a room sound is being reflected from one hard surface to another. The
worst of these types is the dreaded axial mode, which means sound is being reflected from wall to opposing wall or
floor to ceiling. Corners cause us a lot of problems, too, boosting the apparent amount of bass in our rooms by 9dB,
making us think we have 3 times as much bass as we actually do. Corner bass trapping is vital to smoothing out
virtually any room's sound. (Your dealer can advise you how to best achieve bass absorption if you don't have any
90° corners available.)
Some people mistakenly think that making a room's surfaces totally absorbent is the only way to make a room sound
"good," but this is often not the case. While it's true that many rooms' acoustics can be adequately controlled with
60% wall coverage with 2" Studiofoam, the really great sounding rooms tend to be ones with a proper blend and
placement of good acoustic absorption and sound diffusion products. These rooms exhibit a pleasing small degree of
natural ambience, but no flutter echoes or false bass buildup. No products on the market are better suited to giving
you top-notch sound than acoustic absorbers and sound diffusors from Auralex. The BBC did an interesting study and
found that you reap up to 4 times the acoustic absorption if you spread your absorbent material evenly around a room
instead of putting it all on just one wall or ceiling. Just how you spread the material around is based largely on
what appearance you desire, so come up with a treatment scheme you enjoy the looks and sound of. Another added plus
to spreading your acoustical foam around is that you get some extra (beneficial) sound diffusion off the exposed
panel edges of the panels.
There are some folks who prefer a more live, yet controlled, environment. The best way to achieve this sort of
acoustic character is to use corner bass traps, thinner absorbent materials on the walls and ceiling and extra
amounts of 3D sound diffusion. This treatment package imparts a controlled spaciousness to sound. Diffusion is
virtually universally recommended for live studios and control room rear walls. Also perfect in these types of rooms
are Sunburst Broadband acoustic Absorbers, which look great, absorb really well and allow you to gain significant
sonic control without excessive deadness.
There are places where a very dry, controlled acoustical environment is definitely called for; a couple examples
are voiceover booths and radio studios. Drying these rooms out ensures that when a talent is speaking into an open
mic, all you hear is an up-close, direct, present sound - you don't hear a bunch of detrimental room ambience.
Listen to network-quality voice work - you virtually never hear the "room." As listeners, we've become so accustomed
to this type of sound quality that when we hear a person speak on television and radio, we expect their voice not to
sound like they're in a cave. On those occassions when it sounds like they are in a cave, the ambience really sticks
out like a sore thumb and sounds cheesy to us. My point being, if you desire liveness, it must be well controlled in
order to sound pleasing and professional.
Click Here for a brief introduction on how Auralex Studiofoam-based products are made. For more in-depth educational materials, download the PDF version of our handy booklet Acoustics 101 (4.4Mb) or visit Acoustics101.com!