Let's make music more fun & accessible 🙌
I build tools at the intersection of music, technology, and learning.
A little about me
Music has been a big part of my life. I've spent years studying and playing piano, music theory, and history, and have also played flute, sung in choirs and a cappella groups, taught piano and music theory, and more recently started learning guitar.
All those years of playing and studying music shaped the way I think about harmony. I tend to organize musical ideas visually and intuitively in my head, and that way of thinking eventually became the foundation for Gesture Synth.
MY MAIN PROJECT
Gesture Synth
Gesture Synth is a browser-based musical instrument created by Eric Wei that uses hand tracking to let you play chords with your hands while singing the melody yourself.
I designed it around the idea that the instrument should handle the harmony while you provide the melody with your voice. In that sense, it's a little more like a ukulele than a piano: you use simple gestures to move through useful chords while you sing.
Why I built it
I had seen hand-tracking instruments and vocoders online, but many of the musical interfaces I came across treated gestures like buttons in the air: make one gesture and trigger one sound.
I wondered whether hand tracking could be used for something more expressive — especially for chords. Rather than pressing invisible buttons, I wanted the gestures themselves to represent musical relationships.
I quickly realized this new medium unlocked many expressive possibilities. Hands can create different shapes, move in three dimensions, and tilt in different directions. I wanted to use those capabilities to create a system where the gestures themselves represented musical relationships.
The result was a system where your hands navigate harmony instead of simply triggering individual notes.
HOW IT WORKS
Play with your hands.
Gesture Synth uses hand tracking to turn simple hand movements into chords and musical expression. The left hand chooses the chord, while the right hand controls how it sounds.
LEFT HAND
Choose the chord
Fingers → chord degree
Tilt → major or minor
Tilt your hand inward for major and outward for minor. This lets you move between the two harmonic worlds without changing the chord shape.
RIGHT HAND
Shape the sound
Fingers → chord voicing
The thumb moves the chord down one octave.
Position → expression
Move your hand higher or lower to control volume. Tilt your hand to sweep the filter and change the character of the sound.
How it started
JULY 6, 2026
This is the day I posted my first video of Gesture Synth. When it was still a localhost with no real domain. The original version already had the core gesture system used today. The main difference was that the right hand initially controlled the density of the chord — essentially how many notes were played at once. I later changed that to control different chord voicings because it gave the player much more musical expression.
JULY 11, 2026
The was the first time I put it online with Vercel so anyone could play it in their browser.
JULY 19, 2026
I posted a version of Madonna's Like a Prayerusing Gesture Synth. It became the first Gesture Synth video to reach one million views on Instagram.
JULY 20–23, 2026
More videos followed, including Hit the Walland Avicii's The Nights. As more people discovered the instrument, they started asking how they could use it themselves, so I published a tutorial on July 23.
The project took off
A few of the early videos that helped introduce Gesture Synth to a much larger audience.
July 19, 2026
Like a Prayer
The first Gesture Synth video to reach one million views on Instagram.
Watch on Instagram →
July 20, 2026
Hit the Wall
One of the first videos to take off after Gesture Synth went public.
Watch on Instagram →
July 22, 2026
The Nights
Another early viral demonstration of the instrument.
Watch on Instagram →
July 23, 2026
Gesture Synth Tutorial
A tutorial showing how to play the instrument.
Watch on Instagram →
From experiment to community
As Gesture Synth spread, people around the world began experimenting with it and making their own covers. Creators such as Liv Angell and saaisha.music helped introduce the instrument to even more people through their own performances.
I also made the code public on GitHub so people could explore the project and build their own versions. Since then, other independent projects have emerged that were inspired by the Gesture Synth concept and gesture system, including GestureSynth.com and Gesture.live.
Those projects are independent and are not affiliated with Eric Wei or this site.
Today, the main home for my work on Gesture Synth is indecisiveeric.com, where I'm continuing to develop the original project and explore future versions and extensions.