Science+Behind+Exhibit

Just so we have a copy of it on the wiki, here is the report on the science behind the exhibit.

**The Science Behind “That Sounds Cool”** Leila, Gwynne, Drew, Scott, Brittney, Marshell

Our exhibit introduces visitors to the visualization of sound. The idea is to create a room that allows sound waves to become visible. In order to enhance the experience and aid in the functioning of the room, it will be soundproof//.// Visitors will make sound by using a microphone or by playing songs from their MP3 player. This sound will be made visible by projecting the recorded sound waves through 3D-space. The wave color that is projected will vary by sound frequency (the visible light spectrum is superimposed onto the audible sound spectrum). A band of light that changes colour will create a challenge; the visitors match the colour of their sound wave with the colour of the light band. Not only are visitors gaining an understanding of what sound ‘looks like’ but they also engage in a fun activity that enhances the experience of the science behind it all.

Firstly, we have the concept of a soundproof room; the purpose of which is to block any sound from outside that would interfere with the sound waves being created or projected on the inside of the room. Soundproofing is accomplished by using materials that absorb (materials absorb the vibrations caused by sound) and dampen (materials that ‘kill’ sound and do not vibrate) sound. The wall will be made of dense heavy material such as concrete or lead with large air gaps in between, allowing the sound to remain in the air gaps. Other materials that can be used to absorb sound are fiberglass, neoprene rubber, viscoelastic foam, or mass loaded vinyl. An optional method to use is decoupling, in which essentially a room is constructed //within// a room. Each room is made from heavy, solid materials but the two rooms cannot be touching one another directly or sound will pass through (a vacuum or air pocket must remain in between).

A visitor will enter our exhibit and do one of two things: talk or sing and be able to see that sound wave or plug in an MP3 player and see a song visualized. If the visitor chooses to talk or sing, their produced sound will be recorded by microphones placed around the room. The microphone sound signal will be analyzed by an oscilloscope to produce a transverse wave of the visitor’s sound. In the case of the visitor listening to an MP3 payer’s output, the audio stream will pass through a computer which can calculate the transverse waveform of the audio stream without the use of an oscilloscope. (//NOTE//: Sound travels as a longitudinal wave, not as a transverse wave; this is only used a model to better visualize it. In our exhibit, there will be a switch to change the projection from one type to another - a computer program can be written to convert a transverse wave into a longitudinal one).

Seeing this sound waveform in 3D space requires the use of a neat projection technology. This technology requires the use of a mist or dry ice machine (preferably a mist one) and a fan that can expel air through two slots. The air and mist will be ejected from a unit that hangs from the ceiling. The fog that comes from the mist machine will pass through tubes that are cooled by ice (or another mechanism). This is to increase the density of the fog so that it ‘sinks’ to the floor. Thin air slots will be placed on either side of this fog sheet in order to keep the fog in a smooth layer, preventing it from diffusing. A diagram of this is in our presentation, but it works as follows:


 * **AIR** ||
 * **FOG/MIST** ||
 * **AIR** ||

Now a regular LCD projector can be used with this fog screen in order to see the sound wave. These screens can be arranged within the room to form a circle, and two projectors will be used to create the waveform image (one projector for each half of the circle). Since these screens are constructed from fog and air, a visitor can walk right through the screen as if it does not exist (and not get wet from the fog).

As mentioned before, different frequencies (or ‘pitches’) of sound will be seen via different colour wave projections. The visible light spectrum will be imposed over the audible sound spectrum to accomplish this. Light that can be seen by the human eye is a part of the electromagnetic spectrum. The eye can only detect the parts of the spectrum that fall between the frequencies of 400 - 790 THz. Red has the lowest frequency and purple has the highest.Sound has frequency too: there is a range of frequency that humans can hear (20 Hz - 20,000 Hz). We can make the lowest audible frequency match the lowest colour frequency (i.e. purple with 20,000 Hz of sound). However, the problem with this is that no human can sing at either 20 Hz or 20,000 Hz. The range human voices can achieve is 80 Hz - 1100 Hz. That makes 80 Hz = red and 1100 Hz = violet. Anything over will become purple, anything under will be red. A computer program can easily work out which frequency corresponds with which colour.

Our exhibit incorporates the science of sound into a fun, interactive, and engaging exhibit that will surely teach every visitor something about sound.

**Works Cited**

Building a Soundproof room within a room for maximum sound isolation | Soundproofing Company. //(n.d.).// Soundproofing walls, ceilings and floors. Noise control products and solutions | Soundproofing Company//. Retrieved December 17, 2010, from// [] //Conger, C. (n.d.). TLC Home "How to Soundproof a Room".// //TLC "Guides"//. Retrieved December 17, 2010, from [] //Describing color//. (n.d.). Retrieved from [] //Sound properties and their perception//. (n.d.). Retrieved from [] //Understanding STC and measuring Sound Loss | Soundproofing Company.// (n.d.). //Soundproofing walls, ceilings and floors. Noise control products and solutions | Soundproofing Company//. Retrieved December 17, 2010, from [] //Uses of the Oscilloscope.// (2010). Retrieved December 13, 2010 from eHow: [|http://www.ehow.com/about_5348699_uses-oscilloscope.html]. //What is an Oscilloscope used to Measure?// (2010). Retrieved December 13, 2010 from HowStuffWorks: [|http://science.howstuffworks.com/environmental/energy/question8.htm].

Finkbuilt. (n.d.). Finkbuilt » Blog Archive » DIY Fog Screen. finkbuilt. Retrieved December 13, 2010, from []

Russell, D. (n.d.). Longitudinal and Transverse Wave Motion. PAWS - Personal Accessible Web Space - Kettering University. Retrieved December 13, 2010, from http://paws.kettering.edu/~drussell/Demos/waves/wavemotion.html