These are the physical and acoustical properties of the space. This involves the size, shape, and the absorptive, reflective, and transmissive properties of the floor, walls, ceiling, and any other materials in the space. Think of absorption, reflection, and transmission as a triangle. The sum of the degrees of a triangle always equals 180, and it is the same principle with sound energy in a space. If it’s not absorbed, it’s reflected. What’s not absorbed or reflected is transmitted into an adjoining space.
The shape of the space is also a consideration. Avoid domes and curved walls, as these will focus sound energy in undesirable ways.
If the space also functions as a gym, it’s typically a bigger room with a high ceiling. Normally, it will have hardwood floors, painted CMU (concrete masonry units or “cinder block”), and some sort of steel ceiling. The result is little in the way of energy absorption, thus providing for lots of reflective energy. Even if they have wall pads, they aren’t of much help for absorption.
If it’s just a cafatorium, your ceilings may be 10 feet or so. These rooms typically have tile floors, painted CMU or gypsum walls, perhaps large windows, hopefully with acoustical drop tiles. Even with acoustically absorptive drop tiles, that’s absorption on only one of the six sides of the box, so these are typically noisy spaces as well. The low ceiling may limit you to using ceiling loudspeakers.
As the late John Murray still reminds us with Don Davis before him, “the only thing you can EQ is the loudspeaker.” In other words, the electronic adjustments performed during the equalization process can only affect the response of the loudspeaker. Once the sound leaves the loudspeaker, it’s out in the wild. The room itself, the room acoustics, will imprint its signature on the sound before it arrives to the listener. You can’t do anything about what happens to the sound between the loudspeaker and the listener unless you change the acoustical characteristics of the space.
Engaging a qualified acoustician at the beginning of any project of significance can help you design great sounding spaces. Many years ago, there were some commercials related to car maintenance that used the line, “Pay me now or pay me later.” It’s also true of the acoustician. The trouble here is that hiring the acoustician after everything has been built usually comes after a number of equipment upgrades that were intended to “fix the sound.” Additionally, implementing acoustic treatments after building completion tends to be a whole lot more expensive. Including the acoustician as part of the initial building design team can be a very economical decision.