Cymatics – a way of seeing sound

Our MW5202 Science Dining Symposium would be happening on Saturday (23 April 2016) at the Singapore Science Centre, where the 15 of us would be taking turns to share a science demonstration with you. 🙂 If you haven’t already done so, please register here to get your free entry into the Singapore Science Centre, and join us for a Saturday of Science Dining~~

My demonstration will be about sound waves, and in this post, I would like share with you how I ended up doing this demonstration. Those of you who know me personally would know that my main interest in science is actually in biodiversity and ecology. However, my love for music got me searching for a music related science demonstration…. Which led me to this gem by Nigel Stanford:

I was certainly mesmerized from the start! So, what is cymatics and how does it work?

Cymatics
Simply put, cymatics is basically the study (and some may say art) of making sound waves visible. It has its roots from a Greek word κῦμα meaning “wave”, and was first used as a term by Hans Jenny. This area of science has actually been around for quite a while but has only been made popular after Ernst Chladni’s experiments showing patterns that we now know as “Chladni Figures”.

After watching the video, my immediate response was “Using a Rubens’ tube as a science demo would be so awesome! That’s sure to fire up the audience!” After viewing the behind-the-scenes footage, I convinced myself of the practicalities and safety side of things, and decided that the Chladni plates would be sufficiently fun and engaging enough for a live demonstration.

Chladni Figures
The basic ingredients for getting sand art from sound (aka Chladni figures) are a flat rigid surface, fine particles (flour, sand, talcum powder, salt, etc), and a sound/frequency generator. I spent a few interesting afternoons playing around with different frequencies and amplitudes to form different patterns in the sand, and generally speaking, the higher the frequency, the more complex the sand patterns formed. Yet at the same time, my ears did protest more as I increased the frequency and I had to stop at around 1100hz…

Fret not! A quick internet search shows that there are many people who not only had fun playing with a similar set-up but have also shared their videos 🙂

For those of you who want to hear for yourself how ear piercing the higher frequencies are, and see the transition of patterns from 100hz to 80,000hz, you can check out the video here.

What is happening here is that the Chladni plate would resonant at specific frequencies to form standing waves, and the rigid surface of the plate would have sections that would vibrate up and down and lines where no vibration happens (aka nodal lines). The fine particles would accumulate at the nodal lines, forming the observed patterns. This webpage by PBS Learning Media has a few animations to help visualize how the sound waves interact to give the nodes and anti-nodes.

I would like to wrap this post up with a TED video summarising the potential of cymatics, and hope that you now see sound in a different way!

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