What is the hydraulophone?
The hydraulophone is an acoustic musical instrument that produces sound by means of pressurised water jets. The player blocks the jets with their fingers — like covering the holes of a flute — and each blocked jet creates a sustained musical note. The sound mechanism can be a vibrating reed, a flue pipe edge, or a resonant cavity, depending on the design.
It was formally described and named by Steve Mann, a Canadian engineer and artist, around 2005, though experimental water-sound instruments date back to his work in the 1980s. Today hydraulophones appear in science museums, public parks, music therapy settings and contemporary art installations. The most famous installation is at the Ontario Science Centre in Toronto, where visitors can play an outdoor hydraulophone as a public interactive sculpture.
How it works
A hydraulophone has a row of holes (called jets or flue holes) through which water is pumped at controlled pressure. When a jet is open, the water flows freely and produces no musical note. When you block a jet with your finger, the water pressure is diverted into the sound-producing part of the instrument — a flue edge that creates an air column, or a reed or plate that vibrates — and a clear, sustained tone emerges. Remove your finger and the note stops.
The layout of the holes typically follows a musical scale — diatonic (7 holes per octave) or chromatic (12 holes per octave), depending on the model. The instrument is usually mounted horizontally, with the player standing or sitting in front of it, hands hovering over the jet row.
How to play it
The hydraulophone is one of the most tactile instruments in existence. Playing technique:
- Block individual jets to sound single notes. The harder and more completely you seal the hole, the cleaner the tone.
- Partial blocking creates portamento (sliding between notes) or a breathy, hissing vibrato — the signature "liquid vibrato" that gives hydraulophone music its unique character.
- Multiple simultaneous blocks produce chords.
- Dynamics are controlled by the seal quality: a light touch gives a softer, more airy sound; a firm seal gives a louder, clearer tone.
The learning curve is gentle: first notes emerge within minutes for anyone. Mastering liquid vibrato and clean leaps between non-adjacent notes takes more practice — comparable to learning a recorder, perhaps slightly easier.
Video: hydraulophone in action
The video demonstrates the technique: fingers blocking water jets, the liquid vibrato effect and the flowing, liquid character of hydraulophone music.
Hydraulophone vs waterphone: key differences
These two instruments share the word "water" but are completely different:
| Feature | Hydraulophone | Waterphone |
|---|---|---|
| How water is used | Pressurised jets blocked by fingers — active sound source | Water inside a bowl that modulates pitch as the instrument is bowed |
| Playing technique | Fingers over water jets (like a flute) | Bow drawn along metal rods (like a bowed string instrument) |
| Sound character | Lyrical, clear, melodic — can sound like a flute or organ pipe | Eerie, ghostly, unsettling — used in horror film soundtracks |
| Origin | Canada — Steve Mann, ~2005 | USA — Richard Waters, 1969 |
Uses beyond music
The hydraulophone has found applications beyond concert performance:
- Music therapy — the tactile water contact and immediate sound feedback are especially effective for people with visual impairments or mobility limitations. Touch-based, sensory and immediately rewarding.
- Public interactive installations — outdoor hydraulophones in parks in Canada allow passers-by to make music while playing with water. The instrument functions as sculpture, fountain and musical instrument simultaneously.
- Science education — the hydraulophone makes acoustics and fluid dynamics tangible. Institutions like the Ontario Science Centre and CCRMA at Stanford have featured them.
- Experimental music — the instrument's unique tonal qualities attract composers working in contemporary, ambient and electroacoustic genres.
Can you build one at home?
Yes — there are well-documented DIY hydraulophone projects using PVC pipes, an aquarium pump, and basic flute-making principles. A simple diatonic 8-note hydraulophone can be built for under $50 USD in materials, though calibrating the water pressure and tuning requires patience. Steve Mann has published open-source plans, and several maker communities have shared projects online. It is one of the few instruments where a functional version is within reach of an amateur builder.
Where to find or buy one
Hydraulophones are not sold in mainstream music shops. Your options:
- Ontario Science Centre (Toronto, Canada) — the most accessible public hydraulophone in the world. Free to play as part of the outdoor exhibition.
- Specialist makers — a handful of instrument makers and installation artists build hydraulophones to order. Search for "hydraulophone instrument maker" to find current suppliers.
- Build your own — the most accessible route for home use. Open-source plans from Steve Mann's research are available online.
If you are drawn to water-activated rare instruments, you might also enjoy the waterphone or the ocean drum.
FAQ
What exactly is a hydraulophone?
An acoustic instrument played by blocking pressurised water jets with your fingers. Each blocked jet produces a sustained musical note. Invented and named by Canadian engineer Steve Mann around 2005.
How do you play a hydraulophone?
Cover the water jets with your fingers, like covering flute holes. Each hole is a note; partial covering creates vibrato. Block multiple holes for chords. The water gives immediate tactile feedback.
Is it hard to learn?
First notes come in minutes. Mastering liquid vibrato and clean pitch leaps takes practice — comparable to a recorder or simpler than a transverse flute. The basic learning curve is gentle and intuitive.
How much does a hydraulophone cost?
Diatonic home/educational models: $300-1,500 USD. Chromatic concert models: $3,000+ USD. No mass-market retail supply. DIY versions can be built for under $50 in materials.
How is it different from a waterphone?
Very different: the waterphone is a metal bowl with rods bowed like a string instrument, used in horror soundtracks for eerie sounds. The hydraulophone uses water jets you block with your fingers to make melodic, lyrical notes. They share the word "water" but are not related.
Can I build one at home?
Yes. PVC pipes, an aquarium pump and basic flute-making parts are all you need. Open-source plans exist online. A functional 8-note version costs under $50 USD in materials.