An Audience of the Ruling Houses was a session during which the representatives of the Ruling Houses addressed an individual Homeworlder, usually, but not always, to pass judgment for breaching the Protocols of the Great Houses.
Such Audiences were exceedingly rare, as, for most of the Homeworld's history, (PROSE: The Book of the War) new generations of Time Lords were woven by looms (PROSE: Lungbarrow) with the capacity for disobedience literally programmed out of them. However, occasional impurities in the reproductive matrix did allow for occasional misbehaviour, hence the usefulness of disciplinary Audiences. (PROSE: The Book of the War) One example was the Second Doctor, who was put on trial by three representatives (TV: The War Games) of the High Council, headed by the President, or First Time Lord himself. (PROSE: Doctor Who and the Doomsday Weapon, Doctor Who and the Terror of the Autons)
Since such sessions were very rare, however, by the War in Heaven era, the term usually referred to the two Audiences where Grandfather Paradox was the subject. The first was a rare case of a non-disciplinary Audience as the Grandfather invoked an old tradition to formally declare the creation of a new bloodline, House Paradox, before the Ruling Houses. The second and more infamous Audience was a disciplinary one where the Grandfather was called to account for the illegal alter-time experiments his newly-founded House had been carrying out, most notably the creation of the Eleven-Day Empire, which the Grandfather had not kept a secret from the Ruling Houses, though he had not told them how he had achieved it, nor indeed how it could be accessed. Taking refuge in audacity, the Grandfather appeared before the Ruling House representatives in full bone armour, debuting the look for the first time. This choice was so scandalous as to literally stun the judges into silence, and the Grandfather was allowed to go free. (PROSE: The Book of the War)