Tuesday, 5 February 2013

Water-Hammer Piano as an Interactive Percussion Surface


The paper introduces the proposed use of the natural phenomenon known water-hammer as an interactive percussion surface. Water-hammer, which is generally viewed as an undesirable effect, occurs when water flowing through a pipe is suddenly cut off resulting in a clanging sound. Typically plumbers go to great lengths to stop this effect from happening. The paper presents several carefully designed instruments that use the water-hammer effect to create acoustic notes. Traditional musical instruments make their fundamental sound from vibrations in either a solid (strings and percussion) or gas (woodwinds and brass) whereas the water-hammer's fundamental sound comes from, at least in part, it's liquid state. The paper presents exciting embodiments which have been heavily tested and presented publicly through live performances and workshops in various schools and organisations which have had promising results. 

The Review

The strength of this paper  is in the very well documented process undertaken by the authors of the paper. It is well written and the physics of the instruments are well explained and relativity easy to understand. 

The first embodiment we are introduced to, named "Nessie", is made from twelve pipes.

These pipes have extremely tick walls when compared to the tickness of a normal pipe. This instrument works from water emerging from each of the twelve pipes, named "NessonatorTM"(the word Nessonator is a portmanteau formed from the words “Nessie” (it's name) and “resonator”) and is played by either abruptly stopping the water flow with your finger or hitting it with a rubber mallet. The sudden stop to the water flow creates a forceful impulse, which resonates as a musical note. The music note is depicted by a modified wine bottle which the water passes through, encased in concrete. It is encased in concrete to handle the pressure from the water-hammer and to ensure that the sound is created purely by the vibrations of the water and not the solid that it is encased in. 
In the following video we can watch people from around the world perform on "Nessie". 

As you can hear from the performances in the video, "Nessie" creates beautiful harmonic tones and has a full range scale. While it has a full scale, none of the "hydraulophones" follow the rules of the IPN (Internation Pitch Notation http://www.flutopedia.com/octave_notation.htm) as they ran into five problems with the IPN. To overcome this notion problem, the "hydraulophones" follows the NPN (Natural Pitch Notation where the notes follow a natural order ie. A - G) 

The second embodiment of the water-hammer piano that we see is comprised of solid pipes that are connected to tick elastic walled rubber hoses. 

This instrument is played by slapping the top of the cap, which results in shockwaves that send the column of water into transient disturbance resulting in a harmonic tone. Oscillations occur within the pipes from the interaction between the resistance of water in the pipe, and the elasticity of the end cap on the bottom of the pipe. In this video we see a more advanced version of this protoype being played live in a public performance https://vimeo.com/23136730.

My personal thoughts on both the instruments are positive, both create beautiful harmonic notes and offer musicians and non musicians alike a full interactive musical experience with water. It is the thought's of Steve Mann and the thought's of myself that this musical interaction with water is a way of reconnecting with nature as the human body is mainly made from water. I also found this research to be quite refreshing, we live in a time were everything is going digital and a lot of modern musical inventions have been digital but this paper presents new musical instruments in a very natural organic way. 

Steve Mann and his research team wanted to create a three dimensional experience as the first two embodiments are only one dimensional instruments. With these embodiments the user had to quickly run their hand up or down the instrument to cut off the water to achieve the desired note. A three dimensional embodiment of water can be touched, hit and swirled from side to side in anyway thus making it more interactive. 

To create this three dimensional instrument the researches took inspiration from an ancient African tradition called "Liquindi" (http://en.wikipedia.org/wiki/Liquindi) a form of water drumming performed by women and children from Baka. In groups they hit the water with their hands cupped to trap the air and create a percussive sound. Although to create these percussive sounds both liquid and air (gas) is needed so it is not a hydraulophonic sound. The following video shows a "Liquindi" performance.

The "Water-Drum"

The "water-drum" is an interesting instrument that needs to take many factors into account. Firstly, unlike the other instruments the water-drum needs to be filtered and sub and ultra sonic frequencies need to be pitch shifted to be within the human auditory range. Although these changes are made digitally it does not change the fact that this instrument is an acoustic instrument as the sounds are being processed from an acoustic signal, in the same way an acoustic guitar can be plugged into a mixing desk. The water-drum also needs 8 - 12 hydrophones (underwater microphones) to amplify the signal. Again this does not change the instrument from an acoustic to digital instrument, this instrument is a Physiphone (natural interact for musical expression). The water-drum works by the user percussively hitting the water with their hand, but there is also an added option with the water-drum that you don't get with traditional drums, the user can swirl their hand in any direction cause new harmonic tones. A jet spray can also be sprayed onto the water-drum and acts like that of a bow on a violin, the only difference is the bow effect on the water-drum can be infinite. 

Here is a video of the water-drum in action.

The water-drum is an exciting instrument, and ultimately looks enjoyable to play. It also seems to have a fun social element. I would love to get my hands on these instruments and try them out. From the videos I have watched they seem to perform and as I said earlier they tie in with the natural side of things. 

I am not sure if these instruments will ever surpass the traditional and digital instrument that we use today but I think they are a nice addition to the collection of instruments we have. I think this approach to creating music and instruments alike is very refreshing and exciting.

User tests also showed that these instruments were very popular with people from all demographics.
Here is one last video of the  hydraulophones, here we have Steve Mann and Ryan Janzen perform a duet.

These hydraulophonic instruments can now be found in water parks all around the world. They have also been given to many less well off countries that cannot afford musical instruments. Steve Mann the lead researcher of the paper has worked on many interesting papers and ideas. To find out more about him and this problem follow this link (http://www.singularityweblog.com/cyborg-steve-mann/) to watch a full interview. 
The authors of this paper are as follows, Steve Mann, Ryan Janzen, Jason Huang, Matthew Kelly, Lei Jimmy Ba, Alexander Chen from the University of Toronto.

For more information contact hydraulophone@gmail.com


Steve Mann, Ryan Janzen, Jason Huang, Matthew Kelly, Lei Jimmy Ba, and Alexander Chen. 2010. User-interfaces based on the water-hammer effect: water-hammer piano as an interactive percussion surface. In Proceedings of the fifth international conference on Tangible, embedded, and embodied interaction (TEI '11). ACM, New York, NY, USA, 1-8. DOI=10.1145/1935701.1935703 http://doi.acm.org/10.1145/1935701.1935703

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