When Grammy award-winning composer David Lang was 10 years old, he tapped his music teacher on the shoulder and said: “I want to play in the school band.”

The teacher handed him a trombone and that became the musical instrument he played all the way through graduate school.

“This musical instrument changed my life and that’s why I’m a composer,” said Lang, who won the Pulitzer prize for music in 2008. “All because of my public school.”

This Sunday, Lang will premiere the Symphony for a Broken Orchestra in Philadelphia, where he has written music for 400 musicians – from eight to 83-year-olds – who will play broken musical instruments. That’s right, broken. More than 1,500 broken musical instruments have been sourced from the dusty corridors of the School District of Philadelphia, which has no budget to fix them.

“If there are 1,500 broken musical instruments, that’s 1,500 children who should be playing these instruments and whose lives could be changed,” said Lang. “There is something heartbreaking about it.”

The idea came about last year when Philadelphia curator Robert Blackson was walking through an untended school in south Philadelphia. Broken pianos, which were huddled together in the gymnasium, caught his eye. It sparked an idea to fix the pianos and get them working again.

“It was the tip of the iceberg,” said Blackson, who is the director of Temple Contemporary, an art gallery at Temple University’s Tyler School of Art. “I thought: If there are that many broken instruments in this room alone, how many more could there be?”

He contacted the school district’s music teachers and began collecting hundreds of the school district’s broken instruments. “It kept growing past 1,000 instruments,” he said, “and that’s when I thought, ‘hey, there’s something here.’”

Blackson photographed each instrument and uploaded it to their website “Adopt an Instrument”, where anyone can pay a minimum of $50 to sponsor the repair of a musical instrument from the Philadelphia school district.

After each instrument has been repaired, it will be returned to the public school it came from and put back in the hands of students. So far, 500 instruments are being repaired thanks to donations from online sponsors. According to Blackson, they have already raised $280,000. The money will go toward a legacy fund for the Philadelphia school district, “so they will always be able to repair their instruments in perpetuity”, said Blackson.

Over the past 10 years, the Philadelphia school district’s musical instrument repair fund of $1.3m has been slashed to $50,000. The goal is to raise $1m to replace the original funding cut for the school district’s repair fund.

“What was apparent from beginning is that it’s as much a social and community project as it is a musical project,” said Lang. “These instruments represent something larger than themselves.”

But what does a broken musical instrument sound like? It can’t be that pleasant. However, the composition Lang has written specifically fits the sounds these instruments make in their broken state. “The point was not to end with a beautiful piece of music,” said Lang, “but to raise the money to repair the instruments and get them back into the hands of the children who need them.”

David Lang Photograph: Peter Serling

Consider it an experimental music composition, something along the lines of John Cage, Tony Conrad or Morton Feldman. “We wanted to make sure everyone who played in this piece is represented in the community, not just give intruments to professional musicians,” said Lang.

Among the 400 musicians performing on Sunday, there will be schoolchildren learning to play their first instruments alongside improvisers, jazz, folk and classical musicians and parents. “As a composer, the problem for me is how to write the kind of music that could be played by a wide variety of musicians,” he said. “Most of the instructions are not musical notation where you see notes and staffs, its straightforward instructions.”

Some of the musicians, for example, have taken a broken double bass, laid it on its side and tapped on it with drumsticks. “Some instruments can only be used for percussive abilities because they’re so damaged but they still sound beautiful,” said Lang. “It’s kind of magical, each player discovers what’s unique about the instrument and what it can do.”

On top of fixing the musical instruments, which will be returned to the public schools for the fall of 2018, they are also installing “instrument repair kits” in every public school, which can help with minor repairs.

It taps into not only the sustainability of school funding, but institutional funding in general. “In this country, there is not enough money to supply or fix things or continue the institutions we inherited,” said Lang. “We are using a piece of music to heal this community.”

However, to Lang, this small community project addresses a larger problem. “Today, people are breaking into little tribes and going against each other, but that is the opposite of what everyone learns in music,” he said. “Music teaches people how to be better citizens, how to work in a group and how to overcome problems, we need more of that in our world today.”