Above resonance, wall mass blocks sound, but coincident resonances leak high frequencies

Evidence

As the frequency rises above the partition’s resonant frequency, the masscontrolled region of isolation is entered. In this region, it is the fact that the sound must accelerate a heavy mass that provides the isolation. Because more force is required to move the partition at higher frequencies, the attenuation rises as the frequency rises. At even higher frequencies, there are resonances in which both the thickness of the partition and the way sound propagates within it interact with the incident sound to form coincident resonances that reduce the attenuation of the partition. Damping can be used to reduce the effect of these resonances. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2115

Categorization

• DEFINE: Names the ‘mass-controlled region’ and ‘coincident resonances’ as the two high-frequency regimes of partition isolation.