Let's build a musical instrument that makes sound from vibrations in liquid!
For the first time in human history, we'll give water a "voice".
I recall from my childhood, our kindergarten teacher told us:
"There are 3 kinds of instruments:
- percussion; and
Something bothered me about this categorization because the first two made sound from vibrations in solid matter, and the third from wind (matter in its gaseous state). So I said, "Like the three states-of-matter, solid, solid, and gas?". And then I said "How about a musical instrument that makes sound from vibrations in liquid?" and everyone sort of laughed at me. And when I asked some engineers they said that since liquids are incompressible, what I was proposing was impossible. But if water has exactly zero compressibility the speed of sound in water would need to be infinity, which it is not. So one of my childhood passions was to make, for the first time in human history, a musical instrument that made sound from vibrations in liquids. I ended up making hundreds of different kinds of such instruments: the waterflute, CLARINessie (single-reed water instrument), H2Oboe (multi-reed water instrument), and H2Organ™ (underwater pipe organ); that was enough different kinds to make a whole section in an orchestra, thus creating the "H2Orchestra™" (additional link).
Here's what some of them sound like:
(Instrument I built in collaboration with C. Aimone, played by R. Janzen and I)
Whereas I've invented hundreds of different kinds of H2Orchestra instruments, including those that make sound from other states of H2O, the pagophone (ice instrument), idratmosphone (steam instrument) == remember that H2O can mean ice, water, or steam. I even created a plasmaphone (sound from the 4th state-of-matter). But this Instructable will show just one example of just one kind of water instrument == one that is easy to build at home, even by schoolchildren (many of the other kinds of hydraulophones require highly specialized equipment).
For example, one child at Menlo School was able to successfully duplicate one of my hydraulophone designs (link) by following my research papers, and using the school's laser cutter to make the most difficult part of the instrument (everything else you can get at a hardware or plumbing store). Note that the instrument sounds best when played underwater with no air present anywhere in or around the sounding mechanism. The Menlo School student was playing it in air rather than underwater. It is much harder to make an instrument that sounds good in air. The student did a remarkably good job of making a prototype that works well enough to illustrate the principle, but you will also want to experiment with total immersion of at least the sound-producing part of the instrument.
I call these instruments "hydraulophones", a word I made up from "hydraulic" (Greek, "υδραυλική" for pressurized water) and "phone" (Greek, "φωνή", for "voice"), i.e. the word "hydraulophone" ("υδραυλόφωνο") means the "voice of water" ---- in some sense it gives water a "voice".
I also want to acknowledge the many people involved. Above we see Ryan Janzen, a modern-day renaissance thinker, playing a piece he composed for hydraulophone, together with symphony orchestra. This is the world's first complete orchestral piece, in the sense that it includes all 3 states-of-matter (we did another piece in New York also including plasmaphone for four states-of-matter). Meet our hydraulophone team by visiting Splashtones.com
So let's begin with a very simple hydraulophone design that you can build in a half day or so, ideally with the use of a laser cutter, such as a CO2 laser cutter capable of cutting 1/8th inch or 1/4 inch acrylic.
Step 1: Laser-cut and Test the Hydraulophonic Sounding Disk
One of the easiest kinds of hydraulophones to build at home is the disk-based hydraulophone. It causes jets of water to pulsate at different frequencies, each forming a note on a musical scale.
The only slightly tricky part is making the sounding disk, but if you have access to a laser cutter, this is really quite easy. Be creative in shaping the disk. The number of holes for each track on the disk determine the note for that track. Each track represents one note on the instrument. The shapes of the holes affect the sound (timbre, sound quality, harmonics, etc.). Thus you can even make multiple realizations of the same note, if you want to experiment with a comparison of various timbres. For example, begin by making an instrument that has a dozen realizations of an "A440" note (e.g. all 12 tracks on the instrument being the same note) and then pick out the sound you like best, which is easy to do when all the notes are the same pitch and only the timbre varies from track to track. Then make a new disk using that hole shape for each of the 12 different notes.
You can design your own disk, or just extract the PDF from the figure that appears in this paper (link), which you will notice has 15 tracks (of which we use only 12 since most diatonic hydraulophones have 12 finger jets). Here is also a link to an SVG (Inkscape) drawing of the disk, which can be used as vector graphics to drive a CO2 laser cutter. The best choice of color is one that stands out underwater, yet allows us to see through it, so that it is easier to test. Avoid opaque or frosted acrylic because it is harder to test when you can't see the water jet from the other side (you want to be able to see through the disk underwater to see both sides at the same time). Avoid clear acrylic: its refractive index is close to that of water and becomes almost invisible underwater making it hard to see the disk itself. We used a bright green 1/8" (3mm) acrylic. Serena Gupta used a pink 3mm acrylic.
I want to acknowledge here that our specific disk design in the pictures I took, above, was a collaborative effort between Chris Aimone (presently the Chief Technology Officer of InteraXon) and I (Steve Mann), and further work on this project was a collaboration between Ryan Janzen (the person pictured above) and I.
To test the disk, place it underwater and get a jet of water flowing at the holes. Flow the jet at various tracks (as demonstrated by Ryan Janzen in the above pictures).
Safety first! Wear eye protection, keep hair tied back, and be careful while in close proximity to the spinning disk or water jet. Once the instrument is finished, the disk should be housed in a safety enclosure.
The disk pictured above has 12 tracks, so it can play 12 notes. Test the notes one-at-a-time and make sure they all sound good, before proceeding to the next step.
The disk is attached to a trolling motor, designed for use underwater, and 12 volt operation. The trolling motor has a nice hand-grip that functions as a global pitch-bend grip when playing the instrument with one hand and controlling the motor with the other hand.
Step 2: Construct the Fingerboard and Connect to Tee-fittings
Hydraulophones are generally played by blocking water jets. You can build a hydraulophone that has normal "keys", but there's something a lot more fundamental and primordial about touching water to unleash the voice of water. See the above figure for this design philosophy. Basically I believe that the user-interface should be in the same state-of-matter as the sound production. More on this philosophy of musical instrument design here (link)....
Its also a lot more expressive to touch the water itself, rather than touching levers or keys or other contraptions.
So if you're in agreement, the next step is making the fingerboard.
Basically it comprises 12 "Tee" fittings, you can get a plumbing shop, and water goes through each of them from one end to the other, with a hose from the side-discharge feeding to the hydraulophone disk.
So the next step after you build the fingerboard is to connect it to the hydraulophone disk.
Step 3: Connect the Fingerboard to the Hydraulophone Disk
At this point, you can continue using the same disk, or, if you're finished with all the testing, a more durable (and therefore louder!) disk can be printed on a more tough plastic, or on stainless steel (you won't need to be able to see through the disk anymore once you enclose it in a housing and operate it remotely by the fingerboard).
Finally, connect the side-discharge of each "Tee" fitting to a hose going to the disk. You will now have 12 hoses going to the disk.
Now make the sounding bar. For this, we took a round acrylic rod (transparent cylinder) and drilled holes in it, one for each note. The 12 hoses end at the sounding bar, where they discharge onto the sounding disk, at very close proximity (almost touching).
Here there are 12 notes, 12 tracks, 12 hoses, and 12 jets. One hose is for each jet. There are six hoses on each side of the disk. One side does even numbered tracks, and the other side does odd-numbered tracks. This makes it easier to get the hoses together, and makes the hole spacing more manageable in the acrylic sounding rod, while allowing all 12 hoses to be held by the same acrylic sounding rod.
Now you can play the instrument by blocking the water jets.
Put on your bathing suit and have some fun.
Step 4: Playing the Hydraulophone
Playing the hydraulophone is fun. No orchestra or ensemble is complete without all the states-of-matter being present.
Here's some points to keep in mind.
This is an experimental instrument so be patient with the design.
The design shown here is quite quiet. You need to be underwater to hear it well.
You can amplify it with underwater listening devices to play into speakers above the water if you don't want to need to be underwater.
Alternatively, to make it louder, you need to have all the holes working together, not just one. Thus you need a water supply manifold that sprays the water out of each of the holes against another disk spinning (same number of jets as holes for each track). Then it can get extremely loud.
Be careful regarding sound level. When the instrument can be clearly heard above the water, it is very loud underwater, so be careful with your hearing in that case.
Also take care regarding general safety of mechanical systems, such as spinning disks, water spray on surrounding equipment, management of water (keeping away bacteria, etc.), and drowning risks (don't leave a basin setup unattended where small children can access it, etc.).
Be safe and have fun!
Step 5: Going Further: Hydraulophonics As a New Field of Research
Hydraulophonics brings us a new way of thinking about water, hydraulics, physics, mathematics, music, and the environment.
The piano is "velocity-sensing", i.e. how loud the note plays is roughly proportional to how fast you hit a key. Velocity (speed) is the rate of change of distance (i.e. the slope of the time-distance curve).
Hydraulophones respond to a new physical quantity called "absement" which is the sustained absence from a certain point in space. Absement is the area under the time-distance curve, i.e. the time-integral of displacement, position, or distance.
Thus hydraulophones bring us new ways of thinking about physics, kinematics, etc.. See for example, Jeltsema's paper "Memory Elements: A Paradigm Shift in Lagrangian Modeling of Electrical Circuits" which builds on our work with hydraulophones: "Although time-integrated charge is a somewhat unusual quantity in circuit theory, it may be considered as the electrical analogue of a mechanical quantity called absement. Based on this analogy, simple mechanical devices are presented that can serve as didactic examples to explain memristive, meminductive, and memcapacitive behavior." [Jeltsema 2012].