All fans of sweety type voiced singers resent when someone speaks about manly voiced singers.
Can you imagine sweet boyish voice of Sonu Nigam for actors like Amitabh Bachchan with deep baritone?
There is a reason why Sonu was used for romantic songs in Dabangg while a more manly voice like Sukhwinder was used for title song of Dabangg.
Govinda was always a comedian so I am not surprised that a less macho and more sweet or childlike voice was used for him.
Everyone has own preferences. Vinod Rathod for eg has deep, manly voice and is perfect for Sanjay Dutt which is why he was used in Munnabhai series too. I do not think sweety voiced Sonu suits manly or older actors. He suits romantic or college kid role or less macho actors more. This is why his voice was used for cute or puny Aamir Khan in Fanaa, 3 Idiots and Ghajini.
I am glad Sonu did not work in era of manly voiced and macho actors like Amitabh, Vinod, Shatru or else he would have it really hard to suit their voices and looks. It is his luck that he made it in 90s and 2000s when most actors were keen to play virginal college kids in love.
Udit has mischief in his voice that Sonu does not. I can imagine Tu cheez badi hai mast mast lacking any masala or mischief or lust element if sweet voiced Sonu of 90s sang that song. It would sound more like a college kid eve teasing a girl student rather than a grown ass cop singing for a grown woman at villain's den.
Screenshots you shared are spot on. Kishore da had more manly voice which is why he scored voice of Amitabh and went far ahead in 1970s. Rafi is technically far more accomplished and trained singer than Kishore but it is true his voice hardly suited likes of Amitabh or Shatru. He was hence chosen more to sing for Rishi type chocolate boys. Though Kishore stole a march there too and gave hits like Yeh Vaada raha, Saagar, Karz etc to Rishi.
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