Does low frequency absorption in walls correlate to the low frequency resonant behavior of the walls?
To answer this question before we present the data yes, it does. Perhaps the most important lesson that is taught from this data is that there does appear to be a very strong correlation between the location of resonance in any given wall and the location of the absorption peak of that wall. This should be expected as walls are extremely analogous to typical panel-type bass traps, which are well known to have absorption peaks that correlate directly to the location of the primary mass-spring resonance of the walls. For the purpose of this discussion, let’s assume that there are two basic types of low-frequency resonances in walls. The first are mass-spring-mass resonances, or MSM’s. These involve the air cavity and have traditionally (and incorrectly) been described at times as mass-air-mass resonances. This resonance involves two masses these being the weight of the panels on either side of the wall resonating on a spring. The spring being the air in the cavity of the wall. These sket
