Audience moisture exhaled into a room dynamically shifts high-frequency reverberation

Evidence

In terms of reverberation time, and also the level of the reverber­ ant field, the effect of this extra absorption is to reduce the reverberation time, and the level of the reverberant field, at high frequencies. Fortunately this effect only becomes dominant at higher frequencies, above 2 kHz. Unfortunately, though, it is dependent on the level of humidity and smoke in the venue and so the high-frequency reverberation time, and the rever­ berant 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 Howard, Jamie Angus, coustics and Psychoacoustics, 1986

Categorization

• SHARE: A concert-hall acoustician or sound designer would love this: the audience literally humidifies a room during a show, audibly changing high-frequency reverb.
• QUESTION: How large is this dynamic humidity effect in practice for a full venue, and does it measurably dull a live mix by set’s end?
• corroborated: 2 independent passages support this claim — David Howard, Jamie Angus, coustics and Psychoacoustics, 1986