1. A method of generating a bitstream comprised of a plurality of hierarchical elements that describe a sound field, the method comprising: capturing, via a microphone coupled to a device, audio data representative of the plurality of hierarchical elements; performing, by the device and to encode the plurality of hierarchical elements, a linear invertible transformation with respect to the sound field to reduce a number of the plurality of hierarchical elements that provide information relevant in describing the sound field; specifying, by the device, transformation information in the bitstream describing how the sound field was transformed; and specifying, by the device, the reduced number of the plurality of hierarchical elements in the bitstream.