Reverberation simulates the reflection of sound off of the walls, ceiling, and floor of a room. Depending on the size of the room, and how absorbent or reflective the materials in the room's surfaces are, the sound might bounce around for a long time before dying away.

The reverberation parameters provided by ReverbType consist of the delay time and intensity of early reflections, the delay time and intensity of late reflections, and an overall decay time. Early reflections are the initial individual low-order reflections of the direct signal off the surfaces in the room. The late Relections are the dense, high-order reflections that characterize the room's reverberation. The delay times for the start of these two reflection types give the listener a sense of the overall size and complexity of the room's shape and contents. The larger the room, the longer the reflection delay times. The early and late reflections' intensities define the gain (in decibels) of the reflected signals as compared to the direct signal. These intensities give the listener an impression of the absorptive nature of the surfaces and objects in the room. The decay time defines how long the reverberation takes to exponentially decay until it is no longer perceptible ("effective zero"). The larger and less absorbent the surfaces, the longer the decay time.

The set of parameters defined here may not include all aspects of reverberation as specified by some systems. For example, the Midi Manufacturer's Association (MMA) has an Interactive Audio Special Interest Group (IASIG), which has a 3-D Working Group that has defined a Level 2 Spec (I3DL2). I3DL2 supports filtering of reverberation and control of reverb density. These properties are not included in the JavaSound 1.0 definition of a reverb control. In such a case, the implementing system should either extend the defined reverb control to include additional parameters, or else interpret the system's additional capabilities in a way that fits the model described here.

If implementing JavaSound on a I3DL2-compliant device:

• Filtering is disabled (high-frequency attenuations are set to 0.0 dB)
• Density parameters are set to midway between minimum and maximum

The following table shows what parameter values an implementation might use for a representative set of reverberation settings.

Reverberation Types and Parameters

Type	Decay Time (ms)	Late Intensity (dB)	Late Delay (ms)	Early Intensity (dB)	Early Delay(ms)
Cavern	2250	-2.0	41.3	-1.4	10.3
Dungeon	1600	-1.0	10.3	-0.7	2.6
Garage	900	-6.0	14.7	-4.0	3.9
Acoustic Lab	280	-3.0	8.0	-2.0	2.0
Closet	150	-10.0	2.5	-7.0	0.6