Schroeder Frequency
The frequency above which room modes overlap sufficiently for statistical acoustic analysis to apply.
The Schroeder frequency marks the transition between two distinct acoustic behaviors in a room. Below this frequency, individual room modes dominate and create significant variations in sound pressure throughout the space. Above it, modes overlap sufficiently (typically 3+ modes per bandwidth) that the room's acoustic behavior becomes more uniform and predictable.
This concept, developed by physicist Manfred Schroeder, is crucial for understanding where different acoustic treatments are most effective: • Below Schroeder frequency: Room modes dominate; bass trapping is essential • Above Schroeder frequency: Diffusion and absorption work more predictably
Typical Schroeder frequencies range from 100-300 Hz for small rooms and can be as low as 20-50 Hz for large concert halls.
Formula
fs = 2000 × √(RT60 / V)- fs = Schroeder Frequency (Hz)
- RT60 = Reverberation Time (seconds)
- V = Room Volume (m³)
Practical Example
For a 50 m³ room with RT60 of 0.5 seconds
fs = 2000 × √(0.5 / 50) = 200 HzBelow 200 Hz, individual room modes will be audible. Diffusers designed for 500 Hz won't help with 100 Hz problems.
Related Terms
Room Modes · RT60 · Bass Trap
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