Evaluating sub-100 Hz absorbers for critical listening rooms: Laboratory and in situ approaches

Accurate characterization of low-frequency acoustic absorbers is essential for the design of critical listening environments, where modal control below 100 Hz significantly impacts perceived clarity and tonal balance. This study evaluates the performance of sub-100 Hz absorbers using a purpose-built impedance tube alongside in situ reverberation time measurements. Field measurements were conducted in both small and large critical listening rooms to assess real-world effectiveness, with particular attention to modal decay behavior and spatial variability. Results reveal that while impedance tube data provides useful baseline absorption coefficients, in situ performance is strongly influenced by room volume, modal density, and absorber placement. The findings emphasize the need for integrated testing methodologies when specifying low-frequency treatments in critical listening spaces.