This Room Sounds Too Bright
What is a bright room? We have all heard the expression, this room is too bright. What constitutes a bright room? To determine what causes a “bright room”, we have to look at the surface material of the room. What materials comprise the walls and in particular the walls that surround us on a horizontal plane at our listening position. We also need to examine reflections from these same surfaces.
Parallel, flat, room surfaces create numerous acoustical issues that must be dealt with in a bright room. The parallel surfaces create flutter echo which is a baby echo. It has all the makings of what we would consider to be a full echo but not in the required amount and duration because of the room boundary dimensions. These are termed specular reflections and add to the final sum when it comes to room brightness. We want to produce fewer specular reflections to minimize brightness in our flat surface rooms.
We must create surfaces that when the sound energy strikes it, it is not returned in a patterned and somewhat predictable way. We want the surface to reflect or better yet diffuse the incoming energy into it out into the room in a somewhat unpredictable fashion. The irregular shape of our room surfaces can have a large impact on the redistribution of unwanted reflections.
If one compares two rooms that are the same in surface material, the smaller room will have the lower reverberation time because there will be more sound energy to surface contacts occurring in the room with the smaller size. These surface contacts will also be increased when one measures a particular time interval which will show a higher density of reflections within that particular time span.