An apparatus, comprising: an interface system; and a logic system configured for: receiving, via the interface system, audio reproduction data comprising one or more audio objects and associated metadata; receiving, via the interface system, reproduction environment data comprising an indication of a number of reproduction speakers of an actual three-dimensional reproduction environment and an indication of the location of each reproduction speaker within the actual reproduction environment; and rendering the one or more audio objects into one or more speaker feed signals based, at least in part, on the associated metadata, wherein each speaker feed signal corresponds to at least one of the reproduction speakers within the actual reproduction environment, the apparatus being characterized in that: the metadata associated with each audio object includes speaker zone constraint metadata indicating whether rendering the respective audio object involves imposing speaker zone constraints, and wherein rendering the one or more audio objects includes rendering the respective audio object by imposing speaker zone constraints in response to the speaker zone constraint metadata, and wherein rendering the one or more audio objects further includes rendering the respective audio object either by applying panning rules to map the audio object to a plurality of reproduction speakers, or by mapping the audio object to a single reproduction speaker. an interface system; and a logic system configured for: receiving, via the interface system, audio reproduction data comprising one or more audio objects and associated metadata; receiving, via the interface system, reproduction environment data comprising an indication of a number of reproduction speakers of an actual three-dimensional reproduction environment and an indication of the location of each reproduction speaker within the actual reproduction environment; and rendering the one or more audio objects into one or more speaker feed signals based, at least in part, on the associated metadata, wherein each speaker feed signal corresponds to at least one of the reproduction speakers within the actual reproduction environment, the apparatus being characterized in that: the metadata associated with each audio object includes speaker zone constraint metadata indicating whether rendering the respective audio object involves imposing speaker zone constraints, and wherein rendering the one or more audio objects includes rendering the respective audio object by imposing speaker zone constraints in response to the speaker zone constraint metadata, and wherein rendering the one or more audio objects further includes rendering the respective audio object either by applying panning rules to map the audio object to a plurality of reproduction speakers, or by mapping the audio object to a single reproduction speaker. receiving, via the interface system, audio reproduction data comprising one or more audio objects and associated metadata; receiving, via the interface system, reproduction environment data comprising an indication of a number of reproduction speakers of an actual three-dimensional reproduction environment and an indication of the location of each reproduction speaker within the actual reproduction environment; and rendering the one or more audio objects into one or more speaker feed signals based, at least in part, on the associated metadata, wherein each speaker feed signal corresponds to at least one of the reproduction speakers within the actual reproduction environment, the apparatus being characterized in that: the metadata associated with each audio object includes speaker zone constraint metadata indicating whether rendering the respective audio object involves imposing speaker zone constraints, and wherein rendering the one or more audio objects includes rendering the respective audio object by imposing speaker zone constraints in response to the speaker zone constraint metadata, and wherein rendering the one or more audio objects further includes rendering the respective audio object either by applying panning rules to map the audio object to a plurality of reproduction speakers, or by mapping the audio object to a single reproduction speaker. the metadata associated with each audio object includes speaker zone constraint metadata indicating whether rendering the respective audio object involves imposing speaker zone constraints, and wherein rendering the one or more audio objects includes rendering the respective audio object by imposing speaker zone constraints in response to the speaker zone constraint metadata, and wherein rendering the one or more audio objects further includes rendering the respective audio object either by applying panning rules to map the audio object to a plurality of reproduction speakers, or by mapping the audio object to a single reproduction speaker.