Expert Weighs in on Speaker Placement

For years the debate among audio enthusiasts was usually what sounded better - analog or digital. But recently, the argument over room acoustics’ importance may have unseated the analog vs. digital issue as the top hot-button topic within audiophile circles.

Driven by the educational efforts of groups such as THX, the Home Acoustics Alliance (HAA), the Custom Electronic Design and Installation Association (CEDIA), the Consumer Electronics Association (CEA), and to a lesser extent in the consumer realm the Audio Engineering Society (AES), room acoustics has become a greater point of emphasis for custom electronics installers.

Beyond the measurement and treatment solutions that are available to installers as part of a complete acoustics package, a major component of the room acoustics equation is the placement of loudspeakers within a small room environment.

The Challenge of Home Acoustics
Norman Varney, founder and CEO of A/V Room Service, Ltd., is one of the top acoustical engineers in the custom electronics market, and he says the problems of residential acoustics run deep.

“Small rooms are containers of sound energy. Most of the sound waves are not allowed to pass by, they return by various means,” he says. “Typical U.S. shell construction materials and methods allow some energy to pass through - mostly low frequencies - some to be absorbed, some to reflect and some to resonate back into the room.

“Often the room is too small to support the lowest frequencies,” he continues. “Standing waves exist and they cause nonlinear frequency response below 250Hz. [The] proximity of speakers and listeners to room boundaries cause reflections to interfere with direct singles causing tonal and spatial distortion. These reflections also cause [the] masking of low-level resolution and limit dynamic range. Flutter echo due to parallel surfaces can be a problem in small rooms [too].”

Varney says the typical residential room presents installers with an environment that sounds slow, muddy and compressed, which in his opinion adds up to an uninspiring listening experience. “A controlled environment presents a very fast, articulate, big and dynamic sound that is very captivating,” he asserts. “It is the difference between disorganized and organized sound.”

Speaker Placement Is Critical
Varney says the reason speaker location is important is that it enables the accurate portrayal of a musical image and timbre. “In a typical room, most of the sound energy perceived is from the room and not the speakers,” says Varney.

Explaining the keys to achieving correct timbre, Varney points out that if speakers are located too close to walls, it is possible that certain low frequencies will become exaggerated and these frequencies will be dictated by a room’s dimensions. Conversely, he continues, if a listener is located in between these room modes (a null) that listener will have a hard time hearing the related frequency. Moreover, if speakers are placed too close to large surfaces, mid and high frequencies will reflect and they will interfere with the sound coming directly from the speakers.

Spatial cues that are a part of a stereo image add to those elements, Varney says. Reflections off of large objects and walls cause the brain to miscalculate a sound’s point of origination, Varney notes. “As reflected sound interferes with the direct sound later in time, our brain fusses their sum and positions the sound incorrectly in space,” he says. “Reflections can also cause changes to the perceived sized of the recorded space and size of individual instruments, depending on our distance [from the point of origin], the frequency and its amplitude.”

As a result, he says, these reflections and standing waves interfere with the recorded signal to distort the original tonality and spatial cues of audio content. “Time, energy and frequency are all affected by the room’s dimension, construction and furnishings,” he points out. “Room modes can easily cause 30dB deviations in the low-frequency range. Mid- and high-frequency room reflections can cause tone colorations and image distortions.”

Audiophile Tricks Deliver the Goods
Years ago, many music enthusiasts set their systems up by using the “golden triangle” rule, which said a listener’s seat should be equidistant apart from his speakers. Varney says that rule is a good starting point even today for a quality two-channel listening experience.

Speakers that are too close together in relation to the listener narrow the system’s soundstage, while speakers placed too far apart aren’t able to create a cohesive soundstage, but Varney says there is some personal interpretation that can be employed within this base guideline.

“Depending on the specific speaker dispersion pattern, room acoustics and customer preferences, you can control the soundstage perspective from a very intimate ‘in-the-band’ type of presentation, to more relaxed, ‘row S’ perspective,” he suggests. “I personally find the best listening location is often a bit farther distance from the speakers than they are from each other. Toe-in also plays a role in soundstage presentation.”