Australia on Thursday (August 11) unveiled plans for the largest renovations to the Sydney Opera House since its opening in 1973, with more than A$200 million ($154 million) earmarked to update the UNESCO world heritage-listed site.

It draws more than eight million visitors a year, bringing A$775 million into the coffers of the state of New South Wales, Deloitte Access Economics said in 2013, but gets low scores from critics and musicians for its acoustics.

The renovations, which kick off next year and wrap up in 2020, will focus on improving the acoustics and accessibility, and convert unused offices into a family-friendly Creative Learning Centre, the Opera House said in a statement.

"This is going to open more of the Opera House to the public, it's going to replace aged equipment and it's going to carefully balance our heritage and our future," said Sydney OperaHouse CEO Louise Herron.

Troy Grant, the Deputy Premier of New South Wales, pledged that the renovations to Danish architect Jorn Utzon's design, which helped make the Opera House one of the world's most recognisable buildings, would not damage the sail-like external facade overlooked by Sydney Harbour Bridge.

Since its opening, however, the structure has never quite overcome the disappointment of its acoustics.

In a 2011 survey of performers, spectators and critics, Australian music magazine Limelight rated the Opera Theatre as having the worst acoustics among 20 major world venues, with its Concert Hall doing marginally better, in 18th place.

That, according to Sydney Symphony Orchestra's managing director, will all change with the new renovations.