The 50-year-old took to micro-blogging website Twitter to mention the specifications needed.
"Hey guys, need your help to spread the word. Thanks. Love. a," the "Ghulam" actor tweeted.
The complete post about the requirement reads: "Aamir Khan Productions is looking for a girl who can sing, in the age group of 12-17. Record a video of yourself singing a Hindi song of your choice and email it (or a link to the video) to: casting@akpfilms.com .
"Please include a short introduction in Hindi and attach a signed letter of consent from a parent/guardian."
Chandan previously used to work for Aamir as one of his team members and has also assisted the "PK" actor's wife Kiran Rao in her films.
The work on the project has started and is at a very nascent stage.
Oscar-winner A.R. Rahman has also come on board for the music of the film.
Aamir Khan Productions was founded in 2001. It is known for launching fresh faces in the industry like Darsheel Safary, nephew Imran Khan and Prateik Babbar.