Make Your Point: Strategies for Home Theater Sound Reflection
Sound control strategies for home theaters can be complicated if the individual methods themselves are not fully understood. Along with absorptive material and corner panel placement comes the need to appreciate the effect of reflection points for top quality sound control in home theater systems.
Sound absorption in home theaters often follows common sound absorption strategies. Many times home theater owners choose to focus their sound absorption attention on strategies that include basically involved the lower half of the wall. Perhaps a chair rail is installed to divide the upper and lower halves of the wall, limiting sound absorption to the lower half, restricting sound absorption to ear level and below. The ideal location for installing sound absorbers is on reflection points. Imagine a little gnome sitting on top of your speaker with a hand full of rubber balls. The spot on the left side at which you have to bounce that ball to hit you in the left ear is the perfect place to put an absorber. Although above the chair rail level, the panel will control early reflections. The same principle is true of the first reflection points of the ceiling, the right wall, and perhaps even behind the primary seating area. The best places for panel placement are corners in a diagonal mounting to control low frequency and the first reflection points off your side walls and ceiling.
To find your first reflection points, there is a way to figure them out using a mirror. While remaining seated in the primary listening/viewing area, have someone hold a mirror flat to the wall and move it around. The reflection point is established when the speaker is visible in the mirror. However, as most people who ever played pool, or billiards, already know, reflection points are easily discernable with the naked eye. For example, if you are sitting in your home theater and you want to bounce a red rubber ball off the left wall and hit your speaker, determine where you would throw the ball to determine the reflection point. Yet another concern of home theater owners is whether or not to add sound absorption to front speakers. By adding absorption to front speakers, the sound that is heard when facing the front of the room will be from the speakers and not from any reflections off the front wall, making the speakers sound more precise.
For additional early reflections points, a panel should be installed behind each speaker with a third hung in the middle. The closer the listener is to the wall, the closer the first reflection point is to your speaker. For sound absorption directly behind the primary seating area, the closer the listener is to a wall the more the home theater space will benefit from rear-hung panels. The secret is to not overtreat the room. Remove the least amount of objects necessary for a clear, precise sound and leave all other surfaces bare for some echo and reverberation. Finally, when sound treating smaller rooms, it is recommended to use the thickest panel possible. If there is simply not enough room for the thickest panel on the market, a thinner panel is the most practical. Aside from the acoustics, the overall goal is to furnish the available space to be comfortable and aesthetically pleasing.
Home theater acoustic rules are made to be broken. Although thicker panels are naturally better because of better low frequency absorption, they may not always be the most reasonable for the available space. When possible, it is recommended for home theater owners to use thicker sound-absorbing panels. There is a perceivable benefit for the listener and the overall cost is negligible.
Bouncing Back With Big Sound: First Reflection in Small Rooms
The task of sound control for home theaters owners comes in many forms depending on the frequency of sound and the size of the home theater space. Controlling sounds in both the low and high frequencies is imperative to guaranteeing the quality of sound desired for the maximum home theater experience. The control of low frequency sounds is commonly referred to as bass trapping while controlling high frequency sounds is known as first reflection.
As far as home theater sound control goes, first reflection is in essence the opposite of bass trapping. First reflection is a completely different sound problem that comes with the small home theater room. The home theater system setup in a small cannot create a sound field that is easily heard to it as it moves from right to left. Rather, the sound bounces arrive at the listeners’ ears in a very short time after the initial impulse. The actual sound heard is hardly what the creative artists intended the viewer to experience. The sounds that are clearly emitted from the speakers are perceived in an unclear manner because two to three versions of the sounds are heard a few milliseconds apart in time. What is actually heard is a muddied, unintelligible tone.
One of the biggest mistakes people make in home theater treatment is installing a lot of thin treatment for early reflection controls. The sound control priority is to address the problem with low frequency control. The best way to accomplish dual sound control is to use a thicker panel, for example four inches, instead of a thinner 1-inch panel. The benefit is both low and high frequency absorption in the room. The cost is essentially the same with a better sounding room. To solve the sound problems of the small room, corner panels should be mounted in the theater room in most of the available but convenient locations.
The suggestion for home theater owners with small rooms is to put a pair of 4-inch thick, 8-foot panels at opposite diagonal corners for a room with four available corners in the room. The panels are then 45 degrees to each wall touching at two walls and stacked up floor to ceiling. For side wall and ceiling panels should be restricted to one panel on the left and one on the right for each row of seating, with three to four panels hung from the ceiling, and one to two panels on the rear wall. Complete sound absorption is achieved without the dull and lifeless sound in the high end that results from over-absorption.
Small rooms offer a challenge to home theater owners looking to achieve successful sound control. Without the need for technical understanding, both low and high frequency sound absorption can be achieved with the proper size, amount, and placement of panels throughout the home theater space.
