I ran across this web site recently and have found it very interesting and confusing:
http://www.recording.org/users/acoustics/The author explains small room acoustics in a way that makes sense, yet is opposed to a lot of the common theories of controlling bass, and/or setting up a listening room that I have been used to. In the past J. Gordon Holt placed together several articles on setting up a proper listening space. These are the ones that I have followed. Here is a man with years upon years of experience in such matters. But, in fact this other fellow here, Ethan Winer, also has years of practical experience. Yet they both oppose each other in a complete 180 degrees.
Basically, Mr. Holt attests to the fact that for an ideal listening space and bass response, the room must contain the bass energy and prevent it from leaking out. Then it can be treated and controlled as necessary. Mr. Winer on the other hand states that zero boundries, or 100% absorption preventing any bass reflections are the ideal. Below I have copied and pasted a small section of that general article that deals with this specific issue.
BIG WAVES, SMALL ROOMS - by Ethan Winer
There is a common myth that small rooms cannot reproduce low frequencies because they are not large enough for the waves to "develop" properly. While it is true that low frequencies have very long wavelengths - for example, a 30 Hz wave is nearly 38 feet long - there is no physical reason such long waves cannot exist within a room that is much smaller than that. What defines the dimensions of a room are the wall spacing and floor-to-ceiling height. Sound waves generated within a room either pass through the room boundaries, bounce off them, or are absorbed. In fact, all three of these often apply. That is, when a sound wave strikes a wall some of its energy may be reflected, some may be absorbed, and some may pass through to the outside.
When low frequencies are attenuated in a room, the cause is always canceling reflections. All that is needed to allow low frequency waves to sound properly and with a uniform frequency response is to remove or at least reduce the reflections. A popular argument is that low frequencies need the presence of a room mode that's low enough to "support" a given frequency. However, modes are not necessary for a wave to exist. As proof, any low frequency can be produced outdoors - and of course there are no room modes outdoors! Top
Here's a good way to look at the issue: Imagine you set up a high quality loudspeaker outdoors, play some low frequency tones, and then measure the frequency response five feet in front of the speaker. In this case the measured frequency response outdoors will be exactly as flat as the loudspeaker. Now wall in a small area, say 10x10x10 feet, using very thin paper, and measure the response again. The low frequencies are still present in this "room" because the thin paper is transparent at low frequencies and they pass right through. Now, make the walls progressively heavier using thick paper, then thin wood, then thicker wood, then sheet rock, and finally brick or cement. With each increase in wall density, reflections will cause cancellations within the room at ever-lower frequencies as the walls become massive enough to reflect the waves.
Therefore, it is reflections that cause acoustic interference and standing waves, and those are what reduce the level of low frequencies that are produced in a room. When the reflections are reduced by applying bass traps, the frequency response within the room improves. And if all reflections were able to be removed, the response would be exactly as flat as if the walls did not exist at all.
