PHOTO COURTESY GIK ACOUSTICS (the speaker locations and the listening position) and/or adding acoustic treatment. A good bass trapping strategy will result in much better readings with a much flatter response; often adding bass traps will take a room like this from ±30 or 40 dB down to ±10 to 15 dB or better, which is a huge improvement (don't forget, decibels are a logarithmic scale, not linear). 6 SPL OVER TIME: WATERFALL GRAPHS But sound and room acoustics aren't ever mere snapshots in time like the SPL graph shows. Sound in a room changes over time, so we need more tests than the SPL graphs. There are a few ways to look at time's influence on the room's sound. Because it's closely related to the SPL graph, let's look at the waterfall graph in Figure 4. Waterfall graphs are arguably the sexiest aspect of this otherwise very geeky endeavor of doing science by measuring our rooms. They also give us 7http://cras.edu