VOCAL SYNTHESISERS
kim's comprehensive guide 
what is a vocal synthesiser?
dictionary definition will tell you that a vocal synth is a noun, meaning "a computer system that is used to artificially produce the human voice", and while that is true, in this case we're discussing a specific few programs created to (among other things), make music. basically, it's an instrument—the 'voices' are made from clips of real people making sounds (a, i, u, e, o, etc.) then fed into an engine, which works on a piano roll system similar to those used in any synthesiser, and can then be edited and changed to make different tones and sounds.
so if it's music, who makes it?
the people who make vocal synthesiser songs are called producers and they’re the ones who’re in charge of tuning the vocals, making the instrumentals and writing lyrics. some producers do it all themselves, though others work in teams or collaborate with other producers to make songs. majority of producers have the suffix '-P' at the end of their name to show that they're a producer, though in recent times a lot of newer producers do not.
no two producers songs will sound the same, unless they're directly trying to copy another's style. each producer has their own style of tuning, and their tuning style is the hallmark in their music that seperates their songs from one another. as an example, this is "i'm not a devil" by pinocchio-P and deco*27. in this song, both producers use miku, but because of their different styles, she sounds totally different.
what voice banks are there?
there are more than a hundred vocal synthesisers out there, and it would be insane to try and list them all in one place. that being said, there are definitely more popular voicebanks. the most well-known is hatsune miku, who's become something of an idol for majority of the world's anime fans. other famous VOCALOIDs include kagamine rin and len, kaito, meiko, megurine luka, and megpoid gumi.
however, VOCALOID isn't the only company who make synthesisers, despite them being the most well-known. some other popular synths, VOCALOID and otherwise include kasane teto, an UTAUloid who recently got a SYNTHV voice bank, kafu, a CeVIOloid, and vflower, who was originally a VOCALOID but now has a CeVIO voicebank.
synthesisers i'm personally a big fan of include fukase, whose voice provider is fukase from sekai no owari, ZOLA project, a set of three voices in one set (kyo, will and yu), luo tianyi, a chinese voicebank, and seeu, a korean VOCALOID whose voice provider was sent to jail for tax fraud and voicebank taken off the market. she was also the first korean VOCALOID ever released.
where do i start listening to music?
there are so many answers to this question, and most people will tell you something different. listening to the older songs is where i would personally recommend you start, but you can also listen to the most popular songs, or if you have a favourite genre, find a producer who makes music in that style. minnemi has a video on 100 iconic VOCALOID songs, which also has a sequel, and there's a playlist of older VOCALOID songs here.
this is my playlist of vocal synthesiser music, and i've been updating it on and off since 2021.
derivatives, fanworks and other trivia
some fun extra things that i think are cool enough to be mentioned:
- akita neru, despite never having a voicebank, became popular enough as a parody character to become officially recognised.
- yokune ruko, an intersex UTAUloid whose voicebank is one of the coolest things i've ever heard. she's obsessed with gambling and is 12 (???)
- utane uta / defoko, the default voice for UTAU, which comes preinstalled. her voice is hard to tune, but sounds very robotic which i find cool
- acme iku, a synthesiser whose voicebank consists of only moaning sounds. she was rerecorded in 2023 and has been used to make songs, such as chaosmaid by paraoka
- HACHI, a famous producer who also happens to be kenshi yonezu, a chart-topping japanese musician who was responsible for the MHA theme song
- UTSU-P, to be honest, i just wanted to mention him because he's one of my favourite producers. he creates VOCAMETAL, which is pretty self explanatory.
- project diva, the mother of all VOCALOID rhythm games, still available today!
- MMD / mikumikudance, a freeware 3D animation software that was originally used to create miku MVs
- project sekai / colourful stage, a terrible awful rhythm game featuring ocs for 14 year olds to kin. it's responsible for a lot of current-day VOCALOID content