Dunedin Town Hall Organ Trust members demonstrated the symphonic organ's full vocal range and inner workings at an open day.
"Organists have their own language and we talk about 'families' of pipes. All the families of pipes speak in different pitches to make a full-bodied and bright sound," Dunedin City organist David Burchell said.
"The idea is to try to reproduce the sounds of the orchestra as closely as possible."
Mr Burchell, who worked as an apprentice organ-builder in the 1980s, was appointed Dunedin's official city organist in May.
Dunedin Town Hall Organ Trust chairman Peter Stockwell accompanied the talk with a demonstration of the many parts of Norma's repertoire, including her flutes, clarinet, trumpet and strings.
The 23-tonne Norma was christened the "Bathurst Mammoth Cathedral Organ" when built in England in 1919.
It was later installed in Wembley Stadium for the 1924 Exhibition, before being brought to Dunedin and placed in the town hall in February, 1930.
The organ has 3500 pipes - the majority of which are hand-made from tin and lead - including a 2.5m bass flute, 5m double trumpet and a 5m trombone.
The actual organ interface is like the inside of a jumbo jet cockpit made from wood.
