To maintain an optimal level of performance when many sounds are playing simultaneously, sounds below a certain volume level should not take up valuable processing power and memory. Instead of playing these inaudible sounds, the sound engine can queue them in the virtual voice list. Wwise continues to manage and monitor these sounds, but once inside the virtual voice list, they are no longer processed by the sound engine and won’t take up one of the hardware’s physical voices.
When you select the virtual voices feature, sounds move back and forth between the physical and the virtual voice based on their volume levels when they are under threshold or the fact that the playback limit was exceeded and sounds were allowed to go virtual in this situation. As the volume reaches the threshold set by the Wwise user in Project Settings, they are added to the virtual voice list and sound processing stops. As volume levels increase, as is the case when sounds move within the max distance radius, the sounds will move from the virtual voice list to the physical voice where they will be processed by the sound engine again.
You have a choice of three different playback behaviors for sounds as they change from virtual to physical. Each behavior has its own performance characteristics, as demonstrated in the following table:
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| Play from beginning | Medium: Voice stops being serviced when virtual. Some extra operations are done when switching between virtual and physical. |
Low: All internal processing buffers are flushed when virtual. |
| Play from elapsed time | High: Voice needs to be serviced at each buffer when virtual. Some extra operations are done when switching between virtual and physical. |
Low: All internal processing buffers are flushed when virtual. |
| Resume | Low: Voice stops being serviced when virtual. No operations occur when switching. |
High: All internal processing buffers are retained when virtual. |
Streamed sounds stop consuming I/O bandwidth while they are virtual. When the selected behavior is Play From Beginning or Play from Elapsed Time, the I/O buffer is flushed. This causes a delay before the sound is heard again when the voices switch from virtual to physical.
Refer to the Wwise documentation for more information regarding virtual voices from the sound designer's point of view.