User blog comment:Angel Emfrbl/English Vocaloid + realism/@comment-4042934-20150209033635/@comment-53539-20150209090858

Until it can recreate the full capabilities "talent" of certain singers, it will never be a realistic sound. Right now, we get a semi-realistic monotone vocal which, like any machine, produces a manufactured sound.

Sometimes the fans give Vocaloid too much credit to the engine and overstate its capabilities.

But off the bat, a typical example of how unrealistic Vocaloid still is... Lets say Vocaloid says the word "Koi". Well if a human says "Koi" 100 times, every instance will have a SLIGHT variation in the way it sounds, even if its only a 0.000001% (or even smaller) variation. Vocaloid, on the other hand, if you type in "Koi" will say "Koi" the EXACT same way per voicebank. Sure... You can vary the keys and get a slight change due to the note causing the sound to warp, but the sample(s) used to create the word remain identical.

So a Vocaloid is limited, whereas a human singer still isn't, and its that "limitation" that stops any vocaloid currently 100% creating a realistic sound. It goes back to the need for extra tonal voices like the Appends and IA rocks. Or why voices struggle to do songs not within their comfort zone, unlike a human a vocaloid can't "learn" new styles. Miku's V2 is the same in 2007 as it was in 2015, yet in this same amount of time a real singer may have improved or changed styles. The human voice itself becomes more grated over time, so even if a human doesn't change their style, life changes their voice.

All this are factors against Vocaloid's "realism" and why it still has only a "uncanny valley" level. It requires a human to "learn" how to use it, but it cannot "learn" how to become better naturally. This would require a AI system, though I admit I wouldn't mind a actual point in the software if they added a method wherein you can teach Vocaloid itself how to create human vocals more accurately... Be it this is in the realms of Sci-fi and unneeded. Though it would be interesting to see (for example) how Miku adjusted her voice to match 1 person against someone elses experience, at this point Vocaloid would essentially be nothing more then a toy... :-/