Acoustic panels are typically made of fiberglass material and framed in a wide range of fabrics. Panels can be constructed to meet certain room specifications, can be hung from walls and ceilings, and can be propped up with a special stand and moved to different parts of a room. Panels also come in different thicknesses. For example, a 4-inch panel will usually provide better bass absorption than a 2-inch panel, although both thicknesses perform about the same for higher sound frequencies.
Panel fabrics often come in a variety of colors, enabling users to choose one that will be aesthetically pleasing in a room. In addition to solid colors, some companies offer designer fabrics that provide more visual appeal. Colors do not change how sound is absorbed in a panel, but do make the panels align with the room's overall aesthetics.
Acoustic panels act as sound absorbers. The fabric on a panel absorbs ambient sound that comes into a room from elsewhere, such as conversations or traffic from outside. The panels prevents sounds from bouncing off the walls. Positioning acoustic panels in a room allows for clearer recording.
When a sound hits a panel, it is absorbed by the fabric and travels through it. Some panels have wood backing. A sound can bounce off the backing and then get reabsorbed by the fabric. Certain panels have no wood backing, however, and hang a small distance from the wall. In this case, the fabric absorbs the sound, sends it through the panel and out the backside. When the sound hits the wall, it returns back to the panel where the fabric reabsorbs it. Panels with no back are more effective in absorbing bass sounds.
While placement is not absolutely essential, more sound absorption per square foot is achieved when a panel is placed in a corner. Fewer panels are necessary to enable proper noise absorption if panels are placed in corners. Placing panels at points where sound from speakers will arrive is also critical. These reflection points can make a sound arrive late to the listener. For instance, placing panels on the side walls between the speakers and the listener will eliminate late-arriving sound. The listener will hear the original sound more clearly.
Acoustic panels are often mistaken for sound isolators. Sound isolation is achieved by eliminating all outside sound from entering a room, while acoustic panels merely absorb sound and help control how sound travels around a room. To achieve sound isolation, make sure the room is airtight: fill in gaps underneath doors, block air-conditioning vents, and place rigid and heavy items in front of windows (such as a piece of plywood).
Placing acoustic panels in a room brings a host of benefits. First and perhaps foremost, it enables a listener to hear sounds from a source in their most pristine form by eliminating ambient noise. Noise that comes from other parts of a building or outside traffic can have an adverse effect on the overall recording and listening process. Secondly, acoustic panels control the way sound travels through a room. Large rooms with high ceilings are prone to echoes and reverberation, which can permanently alter a sound coming from its source and ruin a good recording or performance.
While room placement is not absolutely critical, some considerations should be made pertaining to the size of the room. Square rooms in particular are vulnerable to four common sound problems: front-to-back flutter, sidewash, primary reflections, and bass imbalance. Flutter is the effect of sound traveling around a room's angularity. Sidewash happens when a sound traveling from its source echoes off the walls surrounding the listener. Primary reflection is essentially late-arriving sound, which first hits a wall before arriving to the listener. And bass imbalance is when low-frequency sounds overpower the rest of the sounds in a room. Strategically placing acoustic panels in such a room can easily eliminate all these problems.