Room reverberation time can be tuned by budgeting open-window-equivalent absorption

Evidence

The results of Example 6.8 beg the question, “How can we improve the evenness of the reverberation time?” The answer is to either add or remove additional absorbing materials into or from the room in order to achieve the desired reverberation characteristic. Here the concept of an open window area budget is useful. The idea is that, given the volume of the room and the desired reverberation time, the necessary open window area required is calculated. The open window area already present in the room is then examined and, depending on whether the room is over or under budget, appropriate materials are added or removed. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1902

Categorization

• DEFINE: Introduces the ‘open window area budget’ — the conceptual bookkeeping device equating 1 m² of open window to total absorption, letting absorption coefficients be summed as areas.
• SEED: Angle: ‘Your room is an instrument’ — a practical essay on treating everyday domestic spaces as tunable acoustic systems rather than fixed containers.
• XREF: connects to: Physical room constraints can make ideal reverberation targets unattainable — David Howard, Jamie Angus, coustics and Psychoacoustics, 1958