For a work celebrating Singapore's Golden Jubilee, it is perhaps ironic that home-grown composer Kelly Tang wrote most of Concerto In Three Movements while travelling abroad.

However, being overseas allowed him to reflect more deeply on what he wanted to bring across in his latest work, says Dr Tang, 53, dean of the School of the Arts.

"Writing this while I was away helped me see Singapore through a more global perspective. It made me realise how significant we have become among the community of nations in the world today."

He was commissioned to create the piece for the Sing50 concert, organised by The Straits Times and The Business Times, and completed it over five months while he was in places such as Britain, the United States and Macau for work.

Concerto In Three Movements will be performed by renowned Chinese pianist Lang Lang, who will lead 50 other pianists aged seven to 52 at the Sing50 concert at the National Stadium on Aug 7. They will be accompanied by the Metropolitan Festival Orchestra.

The concert also features home-grown artists performing popular songs from the past five decades. The star-studded line-up includes Stefanie Sun, JJ Lin, Tracy Huang, Dick Lee, Jeremy Monteiro and Rahimah Rahim.

A Cultural Medallion recipient in 2011, Dr Tang has produced compositions that span a range of genres, from classical to jazz to cinematic music.

The works have been performed by international ensembles such as the Russian National Orchestra, the Ensemble Contemporain of Montreal and the Nagoya Philharmonic Orchestra, as well as the Singapore Symphony Orchestra, the Singapore Chinese Orchestra and the Singapore National Youth Orchestra.

Concerto In Three Movements marks the first time he is composing for Lang Lang and that his work is performed by the Metropolitan Festival Orchestra.

Each of the three movements in the piece pays tribute to Singapore's past, present and future.

The first movement, he says, is filled with "energy, vibrancy and dynamism", while the second is "dignified, slower and reflective".

He adds: "The first movement is a celebration of the present and expresses the vibrant culture Singapore has today. The second movement looks back at the past and is a tribute to the spirit of the late prime minister, Mr Lee Kuan Yew, who committed himself to building Singapore."

To capture Singapore's multiculturalism, the third movement is infused with many Asian music influences and uses the traditional folk song Geylang Si Paku Geylang as its main theme. The 50 pianists will also play together for the last movement in a grand climax.

While Dr Tang was excited to be given the chance to work with Lang Lang, he was well aware of the grand scale of the commission.

"SG50 is such an important thing. I knew I had a big responsibility because the work had to encapsulate that sense of celebration, and half a year would be taken to compose it," he says.

It was a challenge incorporating the sounds of 50 pianos cohesively as he had never written a piece for such a large number before.

"I had to find a way to use the 50 pianos in a way that would not be overwhelming and instead would be tasteful and expressive," he says.

Having worked tirelessly on the piece from February till last month, the composer is happy he can finally unveil the fruits of his labour to the nation next month. He will be attending the Sing50 concert with his wife and two sons, aged 21 and 17.

"I'm proud that this piece is being featured at the concert and I hope it offers a musical experience of a different dimension," he says.

"More than anything, I would like it to connect with people. I hope those who listen to it will be inspired and reflect on what it truly means to be a Singaporean."