Attention-getter, in some rooms

• Bailiff's word
• Cry for attention
• Court order
• Cry from Bull on "Night Court"
• Repeated courtroom cry
• Bailiff's bellow
• Courtroom attention-getting shout
• Court attention-getter

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
early 15c., from Anglo-French oyez "hear ye!" (late 13c., Old French oiez ), a cry uttered (usually thrice) to call attention, from Latin subjunctive audiatis , plural imperative of audire "to hear" (Anglo-French oier ; see audience ).

Wikipedia Word definitions in Wikipedia
Oyez (, , , more rarely with the word stress at the beginning) is a traditional interjection said two or three times in succession to introduce the opening of a court of law , especially in Great Britain. The interjection is also traditionally used by town ...