The Philadelphia Orchestra has commissioned a new piece of music, to feature the voice of you.

Everybody in Philadelphia is invited to download a mobile app to his or her phone, and use it to record anything they want, then upload it to a server. That sound will be used to make a new symphonic composition to be performed next spring.

Composer Tod Machover calls his crowd-sourced pieces "City Symphonies." He works at MIT in Boston to find new ways to use technology to connect people to music. With the MIT Media Lab and Drexel Uiversity's ExCITe Center, he has created not just an app that allows users to make recordings and submit them, but also easy-to-use plug-ins to manipulate sound according to its inherent tonal qualities.

"You'll be able to talk or sing into it and it will pull up 20 other people whose voices have a quality similar to yours," said Machover, whose enthusiasm seems heightened by his flyaway hair. "Or, it might have a bunch of orchestral instruments, and as you talk and the instruments color your voice."

air-dropThe basic app, "Philadelphia Voices," is available now for iOS and Android. It allows users to record, upload, and listen to other people's uploads. The plugins for additional interactive functions are still in development, expected to be ready in a couple months.

Machover was at the Kimmel Center on Thursday evening to introduce the project, which, in order for it to work, requires thousands of people to use the app. He has done similar crowd-sourced projects in Toronto, Edinburgh, Perth, Lucerne, and Detroit, where Machover encouraged residents to explore the soundscape of their city and send him the recordings.

In Philadelphia, he wants to hear voices.

"[Orchestra conductor] Yannick Nezet-Seguin is one of the world's great vocal and choral conductors," said Machover. "Also, Philadelphia has a great tradition of choruses and singing in synagogues and churches all over town. Professional choruses, amateur choruses, there's a great singing tradition."

Two years ago, the Philadelphia Orchestra staged Leonard Bernstein's "Mass," a spectacularly large piece involving hundreds of voices. For its production, the Orchestra invited performers from all over the city to share the stage with its musicians.

"We were thrilled with the menagerie of talent we could bring together in Philadelphia: children's choirs, Mummers, dance troupes, college choirs, instrumentalists," said the orchestra's vice president of artistic planning, Jeremy Rothman. "We loved that collaboration with such great music — but that' such a unique piece of music. There's nothing else like it. So we decided, 'Why don't we try to create these pieces?'"

Rothman said "Philadelphia Voices" is a culmination of the Orchestra's community outreach and education programs.

Machover will listen to every piece of sound uploaded from the app, and compose a piece for orchestra that will include some of those sounds. He does not yet know what its going to be — the sounds will determine what he composes — but Machover hopes the music derived from the citizens of Philadelphia will reflect something of the spirit of the city.

"Whether or not it's about democracy or whatever, it's going to be about the relationship between individuals and large groups," he said. "It's a city, lots of people, lots of forces."

The Philadelphia Orchestra is scheduled to premiere the piece - in whatever form it takes - next April, both at the Kimmel Center and Carnegie Hall in New York.