There are a few things to note about Shantanu Moitra, who is the music composer behind the OST for 3 Idiots. Musically, he seems to favor simple, minimal arrangements - focusing on the mood and theme of the song. But the mood that pervades most of his songs is that of laid back introspection. Even when he's composing a high energy song, its more filled with gleeful energy than any overt paagalpan.
If Shantanu's music doesn't ease the tension in your shoulders after a hard day at work, nothing might.
Such compositions rarely become huge hit singles because they lack the glitz and pizzaz. But the songs are always tightly integrated with the movie, sacrificing hit potential in favor of dramatic consistency (for e.g. no need for shy movie kanya suddenly dancing like a vixen in a promo song).
This comes at a price - big studio releases require super hit songs to settle grab a viewer's flitting attention, thus driving that person into a theater seat come opening weekend.
3 Idiots is the biggest movie of the composer's career. I was curious to see if the resulting pressure would cause him to bolt from his usual style. It didn't - as a result 3 Idiots is signature Shantanu: it won't stick to your ears immediately. But it is, in my opinion, a sharp, smart piece of work.
So what is the CD itself like? Its a bit like a story - it opens with the romp All izz Well, which is an establishing song (new musical term I'm borrowing from cinematography) - used to lay out location (campus) and establish a back story (ignorance is bliss). Because Sonu Niigaam sings the song, we get comedy packaged in superlative melody. Shantanu creates a nifty wind up lead to the chorus and uses inserted sounds and the chorus to propel the off-kilter nature of the track.
Zoobie Doobie (Shreya Ghoshal, Sonu Niigaam) is laid out as homage to the great Hindi love songs of the 60s - the composer runs a bass guitar on an amped down jive beat and adds piano licks and backing vocals in bursts to evoke the sound of Hollywood 40s (also known as Bollywood 60s). Its a little predictable, but its delicate and pretty.
On the third song Sonu sings on this CD - Jaane Nahi - Shantanu alternates between reflection and drama. He starts the tune quietly with an acoustic guitar and almost immediately makes Sonu sing the first verse stridently with a bass drum. Its a pattern that continues through the song.
There are other songs on the OST that I recommend you explore - Shaan sings the introspective metaphor for an identity crisis - Behti Hawa and Suraj Jagan shows us some of his supple range on the director's comment, the Dylanesque Give Me Some Sunshine (spoken word by Sharmaan Joshi).
My personal thanks to Shantanu for the help in understanding the CD thematically