The Hydraulophone - A Musical Instrument Played By Flowing Water

A hydraulophone is a musical instrument in which sounds are created by flowing water. The water is pumped into a curved, horizontal tube and then spurts out of a series of small holes in the tube. There is a sounding mechanism positioned upstream of each hole. If a person places a finger over a hole to stop the water jet from emerging, the water flows past the associated sounding mechanism instead of out of the hole. Each blocked hole and its sounding mechanism creates a different note, allowing music to be played. If more than one hole is covered at the same time, multiple notes can be played simultaneously to create polyphony. The player can exert control over the properties of each sound by the exact placement and movement of his or her fingers.

There are many different types of hydraulophones in existence, in different sizes and with different sounding mechanisms. Some instruments are large sculptures in science museums, while others are smaller devices placed in water parks for children to play with. Small instruments are played in concerts. The water flowing out of the holes in these instruments is collected in a trough to be recirculated.

The creator of the hydraulophone is Steve Mann, an engineering professor at the University of Toronto. He’s experimenting with new types of hydraulophones and is exploring new applications of the device. Ryan Janzen, also from the University of Toronto, is a leading hydraulophone player and composer.

The hydraulophone is played like a keyboard instrument but is actually more closely related to a woodwind instrument. In fact, it’s sometimes called a “woodwater“ instrument. The water is pumped through the instrument by an electric pump, a water powered pump, a wind powered pump or a hand pump operated by another person. The sound producing device may be similar to those found in wind instruments, such as a single or double reed or a fipple. (An example of a fipple is the mouthpiece of a recorder.) Spinning disks containing holes have also been used to make sounds.

Another similarity between hydraulophones and wind instruments is the application of embouchure. When a wind instrument is being played, embouchure refers to the shape and position of the lips as they contact the mouthpiece of the instrument. Embouchure affects the nature of the sound that is produced. Similarly, the sound produced by a hydraulophone can be modified by the position of the fingers over the holes as well as by the pressure and velocity of the finger movement. These factors affect the water current hitting the sounding device, just as embouchure in a wind instrument affects the current of air entering the instrument. For example, the sound of a hydraulophone is slightly different depending on whether a hole is approached from the side or from above, and is also affected by partially or fully closing the hole. The sound created at a hole can be "sculpted" and may have a polyphonic quality.

In addition to acoustic hydrophones there are instruments which need electronics to make the sound audible. The water turbulence created when a person presses on a hole and changes the water current produces a sound of its own, but this sound is very weak. It can be picked up and amplified by a hydrophone (an underwater microphone) and then sent to a computer, which plays the sound.

Water park hydraulophones generally have twelve holes arranged in a single row for a one and a half octave range, starting on the A below middle C and going up to E. Key valves provide an extended range on some instruments. More advanced hydraulophones have forty five holes arranged in two rows.

The two hydraulophones outside the Ontario Science Centre in Canada are part of a sculpture. The stainless steel instruments produce their own sounds and also send water out through the openings in large organ pipes, which are driven by hydraulic action. The instruments are available twenty four hours a day. The advantage of water running out of the holes in public hydraulophones is that it helps clean the instrument. In fact, hydraulophones are often said to be "self-cleaning".

Hydraulophones containing solenoid-operated valves have been created. The valves control the release of water from the holes and enable sounds to be produced with no human player involved. If the valves are disabled the instrument can be played in the usual manner.

Some hydraulophones are covered by a colorful material. They have one end that is enlarged and has an opening that looks like a mouth, and an extra curve at the end, looking like a tail, making the hydraulophone look like a strange water creature. These instruments have been nicknamed "Nessie". All hydraulophones work in the same fundamental way, but they vary considerably in their sound producing devices. The "Nessie" shown in the first video in this section has acoustic enhancements to make the sound even more musical.

Hydraulophones can produce concert music for an audience's enjoyment or provide fun for children and adults in parks and museums. They can be used by people who don't know how to play an instrument and by professional musicians as well. They may also have a use in water and music therapy. Many people find playing in water relaxing, and the flow of water jets over the hands can be soothing. In addition, producing music is a creative and enjoyable process. Even hot tub hydraulophones have been created!