Open Air Audio

May 30, 2025

University of Colorado | Boulder County

Hosting open-air celebrations such as graduations and cultural requires sensitivity to audio standards that ensure high-quality sound and audience safety. Today at the usual hour we examine the standards covering sound system design, noise control, loudness levels, equipment specifications, weather and local environmental considerations.

Surprisingly, there are many even without approaching the not insignificant cabling system standards. We pick three representatives titles which cross reference one another:

World Health Organization recommendations for limiting exposure to leisure noise (e.g., concerts) to a level exceeding 80 dBA for 24 hours or 140 dB peak sound pressure to prevent hearing loss. Recommendations for speech heavy events will defer from musical events.

Audio Engineering Society Guideline AES56-2008 which provides recommendations for loudspeaker placement in sound reinforcement systems. Key points include:

- Height and Angle: Line array speakers are often elevated (e.g., on trusses or poles) and angled to cover the audience while reducing sound spill to non-audience areas.
- Distance: Main speakers should be placed to avoid excessive sound pressure near the front (e.g., 95–100 dBA max for audience safety) and ensure clarity at the back.

Acoustical Society of America ASA-2010 Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools. While primarily for schools, this standard’s principles can apply to open-air educational or community events, emphasizing background noise control and speech intelligibility. For open-air audiences at events like outdoor lectures or festivals, speaker placement should minimize interference from environmental noise (e.g., traffic, wind). The standard suggests maintaining a signal-to-noise ratio where speech is at least 15 dB above background noise for clarity.

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