Silent PA also known as Silent Conference Systems allow you to communicate multiple audio (tracks/streams/channels) into the same space, where users can select their channel of choice.
If you need privacy, you can limit the distribution of audio to a limited audience. With multiple video channel choices the audience selects their own soundtrack.
Delegates can move between stations at a venue with different audio tracks. Infrared multi-channel distribution allows up to 32 channels of audio transmission simultaneously.
Each participant carries a receiver and headphone, and selects their desired channel.