There are many uPVC & aluminium windows companies in India which claims to have sound-proof windows e.g. fenesta, tostem, ais windows & eternia windows but they do not have any substantial data like test reports confirming to international standard e.g. EN ISO 717–1 to support their claim.
Now coming back to question, Best sound proof company in India, my answer is - there is no best sound proof company in India. Company like Fenesta has very limited knowledge about sound proofing. Pl check following advertisement Fenesta Windows & Doors - Solve your Noise Problems.
Keep the outside noise out by sliding window- Quite laughable ( Worth to mention- airtightness in sliding window is less than casement window). I am not against Fenesta, they are doing wonderful job in uPVC windows but for sound proofing- it is like dark matter for them. May be my message will get through, and they will improve their understanding for sound proofing.
Also check their webpage over sound proof windows.
Sliding window to stop traffic noise. Amazing ludicrous ignorance !
Casement window has gasket sealing at open/close position in comparison to Sliding windows.
Check another interesting insight on their webpage. They are using silicon for noise insulation. Silicon sealant are good for water tightness, not for noise insulation. PU-Foam must be used for soundproofing.
How the PU Foam installation looks like , Pl check above pic.
Same thing runs with tostem India. Here is the details on their website
There is no performance data mentioned on the products which you will find out in other reputed brand's website e.g. schueco, cortizo & reynaers even uPVC brand also mention their performance data. Also worth to mention ASTM standards are not as stringent as European standards. I will stress only one thing that IF YOU CAN NOT MEASURE SOMETHING, FRANKLY SPEAKING IT DOES NOT EXIST.
Same kind of half baked knowledge as silicone sealant for soundproofing. Once again- Silicon sealant are good for water tightness, not for noise insulation. JIS ( japanese standards) performance data is not shared so can not comment on the same.
Do you want any help for unwanted sound proofing. You can write to me on firstname.lastname@example.org. I can share my knowledge, experience for noise insulation.