What is a vocal synthesizer?

Vocal synthesizers are programs that allow their users to input notes, type in lyrics, and select from a variety of synthesized voices (voicebanks, or virtual singers) to sing the notes back to them! Although they sound choppy and robotic at first, you can fine-tune the voicebank to make it sound how you'd like by editing vocal parameters. Vocal parameters are the "tools" given to the user by the program that let them change how the virtual singer sounds while performing each note. Common parameters include gender factor, breathiness, vibrato, tone shift, tension, and volume. Some programs also offer different vocal modes that allow you to adjust the voicebank you're using to better fit the song you're making with it.

Despite vocal synthesizers being strongly associated with Japan, they offer several different languages across the programs that exist today. Most provide singer languages in Mandarin Chinese, Japanese, English, and Korean, although other languages like French and German have been incorporated by more niche software. Cross-language synthesis has been a recent development that has allowed more and more languages to be sung by virtual singers that couldn't previously sing in more than one language.

Why do people use vocal synths?

Sometimes, a musician might not have the skills or the bandwidth to reach out and contact a singer for their songs. By using a vocal synthesizer, the user can make a one-time purchase of a voicebank and a vocal synth program to provide unique vocals for their musical projects. The voicebanks start out as pre-recorded samples from professional singers (known as voice providers) in a studio, and are then fed through a source-filter model. You can think of a source-filter model as a computer attempting to recreate the sounds it hears. On top of being a one-time payment, vocal synth software gives the user a degree of creative freedom with how the voicebank expresses itself via parameter editing. These are what the user makes changes to in order to produce a different performance with each note. The user can generate all kinds of unique outputs simply by playing around with what the software has to offer.

The current popular vocal synths provide a vast variety of virtual singers to choose from, between both feminine and masculine vocals. Very recently, voicebanks have been developed that are equipped for more difficult and technically-challenging vocal performances, from opera to enka to heavy metal. Developments are constantly being made to provide an even greater range of singing techniques to new and existing virtual singers. Artifical intelligence has also been utilized lately in the scene, providing more realistic-sounding virtual singers.

Frequently-used programs

Vocal synthesis technology has existed since 1961 with the IBM-7094, and has been growing steady ever since. Tens of programs have popped up across the globe to make this technology more accessible to the public. Here's a few of the most commonly-used programs across the general vocal synthesizer community.

VOCALOID

The kingpin of the vocal synthesizer community, VOCALOID has been around since the early 2000s and is currently in its sixth iteration. It was the first commercial synthesizer to see widespread use by the general public, and generally secured the future of vocal synth development. It remains synonymous with the term "vocal synth" due to its massive popularity. VOCALOID is best known for housing the poster child of the community, Hatsune Miku. Since her debut in 2007, she reamins the most frequently used virtual singer on the program. The rise of video-sharing platforms and anime fan culture helped skyrocket Hatsune Miku to wider audiences, as people began creating songs using her voicebanks and designing music videos to go alongside them.

UTAU

As VOCALOID became more popular, many people realized they were barred from contributing to the sprouting internet community surrounding it. Why? Developing vocal synthesizers isn't cheap, and neither was the VOCALOID program. That's where UTAU came in. A single software developer by the name of Ameya/Ayame created UTAU as a free, VOCALOID-like program. Its name comes from the Japanese verb, "to sing" (歌う). Although you couldn't import voicebanks from VOCALOID into the program, users are welcome to make their own voicebanks. As a result, UTAU supports singers in a limitless number of languages, so long as there's a voice that can sing in it. However, UTAU is much more rudimentary compared to commercial programs and has more restrictions on how you can edit the notes, requiring users to seek out third-party software/mods to enhance their experience.

Synthesizer V Studio

Synthesizer V has risen to one of the internet's go-to vocal synthesizers thanks to the quality of their voicebanks. Released in 2018, it has been countlessly praised for the realistic quality of their vocals and the user- friendly design of its interface. They have nearly one hundred different singers on their program as of 2025, with more expected to come. Although the studio version of the software costs money, they also provide a "lite" version of the program for those who can't afford it. The Lite version of the software also has fewer singer options with lower quality sound. Despite this, even at the release of Synthesizer V Studio Lite, the voicebanks were on par with (or sometimes even better than) the most appraised VOCALOID voicebanks at the time.