Looking back at the three thermodynamic issues of absorption, direction and velocity, and combining those factors with practical experience, there are several useful concepts that can be distilled:
1) Humidity variations are sonically more tolerable in higher humidity environments.
2) Consistent temperature throughout the venue is sonically beneficial. Since the temperature of humans is fairly warm, and assuming humans will be attending the concert, having a reasonably warm venue temperature will assist in achieving that consistency.
3) A warmer indoor venue will tend raise in humidity levels more drastically than cooler venues due to human factors.
4) Sonic advantages are achieved by flying the loudspeakers.
5) Mixing a show while standing on a mix riser above the thermal/humidity provides the sound engineer an inaccurate representation of the sound the audience is hearing.
6) Venues with drastic variations in temperature and humidity tend to have complex and unpredictable responses.
7) No matter what you test or measure, a considerable part of the sound of the show is controlled by environmental factors that are constantly changing. Knowing what they are is the first step toward being able to deal with them effectively.
8) A thermometer and hygrometer can be useful tools for tracking and understanding more about how thermodynamics are affecting the sound of the show.
One of my favorite moments of mixing a show is the prediction and anticipation of that first note, the tones, the volume and the intensity of the unknown. The moment when the band first walks on stage is one of the biggest challenges any sound engineer faces. Balancing all that knowledge with the tools at hand and formulating a mix to come up with a clear and accurate result is no easy task.
Each show presents a unique sonic landscape, and it is that uniqueness, that interaction between so many variables that we can and cannot control, that makes every live rock show a one-of-a-kind, potentially magical memorable experience.
Dave Rat heads up Rat Sound, a leading sound reinforcement company based in California.and has also been a mix engineer for more than 30 years.