Design of a multiple-slope sound energy decay system with string and block coupling methods

Driven by the need of both speech intelligibility and music perception, multiple-slope sound decay in a room has been studied for decades. To step further, two different room coupling methods are proposed for achieving decay with quadruple, quintuple, or higher slope numbers. Starting from a triple-slope sound decay system, the understanding of energy flow in such a system is developed as well as the relationship between the decay turning points and the aperture size. Each decay slope represents the acoustic characteristic of the corresponding dominating room, and the dominating durations are determined by the couple condition. Based on the understanding of its energy flow, two different coupling methods, the string coupling and block coupling, are developed for achieving specific non-exponential sound decay with the specific number of slopes, slope values, and times of turning point. These are controlled by parameters including the room quantity, the reverberation of each room, and the coupling aperture sizes. Based on the above coupling methods, a few examples are simulated with the diffusion equation for verifying the energy flux and achieving a specific multiple-slope sound energy decay pattern inside the room.