Audience humidity from breathing changes a venue’s high-frequency acoustics over time

Evidence

Unfortunately, though, it is dependent on the level of humidity and smoke in the venue, and so the high-frequency reverberation time and the reverberant field level will change as the audience stays in the space. Note this is an additional dynamic effect over and above the static absorption simply due to the presence of a clothed person in a space and is due to the fact that people exhale water vapor and perspire. Clearly, then, the degree of change will be a function of both the physical exertions of the audience and the quality of the ventilation system! — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1944

Categorization

• QUESTION: Could a crowded, sweaty concert measurably dull the high frequencies audience hears by the finale? The dynamic range of this change seems worth quantifying.
• CANDY: Audiences change the room’s sound mid-concert just by breathing and perspiring — a fun fact for any live-music lover.