Reverberation Time Calculator

This calculator relies on Sabine's reverberation formula, which relates the volume of a room to its total sound absorption. First, the effective absorption area ($A$) is computed by multiplying each surface area—walls, ceiling, floor, doors, and windows—by its respective Sabine absorption coefficient. The formula for the effective area is expressed as: effective_area = ((room_width + room_length) * 2 * room_height - (number_of_doors * door_height * door_width) - (number_of_windows * windows_height * windows_width)) * walls_coeff + (number_of_doors * door_height * door_width) * doors_coeff + (number_of_windows * windows_height * windows_width) * windows_coeff + (room_width * room_length) * ceiling_coeff + (room_width * room_length) * floor_coeff. Once the total absorption is determined, the reverberation time ($RT_{60}$) is calculated using the room volume ($V$) divided by the effective absorption area ($A$): reverberation_time = 0.163 * (room_width * room_height * room_length) / effective_area, where 0.163 is a constant derived from the speed of sound in standard metric conditions.

Consider a medium-sized practice room measuring 6 meters long, 4 meters wide, and 3 meters high. The room features a concrete floor (coefficient 0.02), a drywall ceiling (coefficient 0.05), standard plastered walls (coefficient 0.03), 1 wooden door measuring 2m by 1m (coefficient 0.10), and 2 glass windows each measuring 1.5m by 1m (coefficient 0.05). First, we find the room volume: 6 × 4 × 3 = 72 cubic meters. Next, we calculate the net wall surface area by subtracting openings from the total wall area, and then compute the effective absorption area across all surfaces, yielding a total absorption of approximately 5.82 sabins. Finally, applying Sabine's equation: 0.163 × 72 / 5.82, we get a reverberation time of roughly 2.01 seconds, indicating a fairly reflective space that would benefit from additional acoustic treatment.

To get the most accurate results from your acoustic modeling, ensure you use accurate absorption coefficients that match the specific frequency you are targeting, as materials absorb sound differently at high versus low frequencies. Remember to account for furniture and human occupancy if you are calculating for a live audience, as objects and people add significant absorption to a room. Finally, if your calculated reverberation time is too high for your intended use case—such as aiming for under 0.6 seconds for a recording studio—introduce porous absorbers or heavy bass traps to increase the effective area.