In a professional recording studio, we have the control or monitoring room. We also have the “live” room. A live room is a room about which we seek to acoustically create a larger sound through higher than normal reverberation times. In a live room, it is necessary to acoustically treat some reflections from room boundary surfaces and let the other reflections run free. We can accomplish this variable type of acoustic presentation with acoustical treatments that allow the engineer to vary the surface of the treatment from absorption to diffusion and even sound redirection. Our acoustic goal for the room and for our microphones is to compliment the individual vocals and instruments. A live room needs to provide at the microphone, an additional amount of analog energy through room sound into our electronic, digital signal path.
In our “live room”, we must have a complete understanding of the size and locations of any room modes. Room modes occur between the parallel surfaces of our room. Because sound waves have certain lengths and travel at a given speed, they become influenced by the room dimensions. Certain parallel room dimensions are more problematic than others, but they exist in almost every room. A room mode will cause an energy field drop out or an energy field exaggeration at certain frequencies or certain frequency groupings. A microphone placed within a room mode that is a null will not let the microphone “hear” all the frequencies produced by the vocals or instruments. If the microphone is placed in a room mode that exaggerates certain frequencies, then one will have distortion at the microphone surface.
Reverberation is another acoustic variable that we need to address. Reverberation in our control room is almost non existent. We don’t want a lot of reverb in the in our control room because we don’t want it to smother or destroy any of the ambiance in our recordings created by our “live room”. In a “live room”, we want to have reverberation, not in our control room. To achieve the proper amount of reverberation is both an art and a science. All one has to do to verify this statement is tour different facilities and listen to their rooms. One will have a big sound that one could record drums in and add a large amount of ambiance to the recording. Another could be good for piano because of its acoustic surface treatment and rate and level of absorption material used.