High Quality Content by WIKIPEDIA articles! Ambisonic UHJ format is a development of the Ambisonic surround sound system designed to allow Ambisonic recordings to be carried by mono- and stereo-compatible media. It is a hierarchy of systems in which the recorded soundfield will be reproduced with a degree of accuracy that varies according to the available channels. Although UHJ permits the use of up to four channels (carrying full-sphere with-height surround), only the 2-channel variant is in current use (as it is compatible with currently-available 2-channel media). In Ambisonics, UHJ is also known as "C-Format".