A listening room can be described as “live” or “dead”, depending on how reflective the walls, floor and ceiling are to sound waves. A live room is echoey, a dead room is non-reverberant. Examples of a live room are a wood paneled church building or an empty warehouse. The best example of a dead environment is the wide-open spaces of the great outdoor plains. Back in the early days of audio there was a standard recommendation for room treatment: Make the front of the room (where the speakers are located) dead and the rear of the room lively. This is the dead end – live end principle. The idea behind this was two-fold. You want the front of the room dead so that near-field reflections won’t compete with the speakers themselves. You want the rear of the room alive to help augment the sense of room ambiance, often not captured in older recordings. But, in these modern days a better way exists.
In any listening experience the sound that is heard is coming directly from the speakers, and again from the room surface reflections. When these reflections are either encouraged or left untreated, two distinct problems arise. The first is an argument between the listening room ambience and the recorded room ambience. The first ambience may be telling the listener that the room is small, while the second is assuring him that the room is much larger. Unfortunately, the first will win the argument, leaving the excitement of the recording venue overpowered and unnoticed. This is, in part, because the hearing perceptic tends to pay the greater heed to what strikes the ears first and, because of their shorter path length, this means the smaller sized listening room reflections. The second problem has to do with the polar dispersion of speakers in general. Most speakers are designed to have their best frequency response directly in front of them, that is, at 0 degrees of azimuthal angle (straight ahead). This is measured and confirmed at the factory by use of an anechoic chamber or similar such means.
What does the speaker do off-angle? Generally, the off-angle radiation is muted, and all the more so as the frequency is increased. The very low bass frequencies radiate very strongly off-axis, while the treble is more beamed straight ahead and muted at off-angles. In the old days of the so-called full range speaker drivers this was not such an egregious problem, but it became much more of a problem with the proliferation of multi-way speaker systems. Consider, for example, a two-way speaker system comprised of a woofer and a tweeter. Being of very different construction and diaphragm size, the woofer and tweeter drivers have very different polar dispersion characteristics. More importantly, dividing the frequency spectrum between these two drivers causes a discontinuity in the polar response of the entire speaker system. Now, place such a speaker in an untreated room and you will have a discontinuity in the frequency response for the wall-reflected energy. For instance, the tweeter may be suppressed at off-angles, making the wall reflections sound muffled and bass-heavy, while the direct (on-axis) radiation will be correct as intended. Additionally, an opposite effect can occur where the tweeter, usually designed to have the broadest possible angle of radiation, reflects from opportune surfaces such as a ceiling, floor, or side walls, forming a distracting addition to the recorded sound. These two effects are not contradictory. They occur because the very high frequencies reflect more efficiently off of untreated walls than do lower frequencies, potentially resulting in a U-shaped frequency response. The older full range speaker drivers were prone to becoming progressively and smoothly more beamed as frequency increases, resulting in an overall boomy muddiness, but the dome tweeter of modern systems gives the broadcast angle a new life at high frequencies. The result is often a superposition of booming, muddy bass with a high frequency edginess, all due to surface reflections. Many a well-designed speaker system has been blamed for this effect when, in actual fact, it is a fault of the room.
Taking these effects together, the best room treatment solution is often that which deadens the room everywhere, resulting in a “dead-dead” room. Admittedly, for recordings that lack any recording venue ambience, for instance the close-mic’ed studio recordings, such a treatment solution offers no help – they will sound quite dead indeed. But these modern days are graced with an enormous proliferation of recordings, and many of them are quite good. If one is willing to spend a considerable sum on very high-end equipment, it is a foregone conclusion that he is also willing to search out the best available recordings. To the degree that he successfully silences his listening room, he is likely to be much more satisfied with the recordings he does find, with his speakers, and with the listening experience altogether. This reality survives the years of searching out audio playback equipment and room treatment solutions, bringing many to eventually conclude that a neutral system is ultimately the best solution to land on. Let the poor recordings sound like what they are – poor. But, let the great recordings sound great. This conclusion seems harder for some to come to than for others, but once arrived at, it is also a very difficult conclusion to deny going forward.
The information contained herein is presented in good faith and with all hopes of helping the reader to find the best equipment for an audio system. Neither the author, nor Bella Sound LLC, assumes any responsibility or liability due to loss on the part of the reader, owing to or believed to be owing to the content of this article, or resulting from or believed to be resulting from an application of the information contained herein, regardless the level of expertise engaged thereto.
