Visual Beats

Overview

---

This project is inspired by Cymatics, the study of visualizing sound through the representation of physical mediums. The common method to visualize sound in Cymatics is by creating a frequency on a plate that vibrates a medium (such as sand or water) placed on top. The more in tune a frequency is to the plate, the more complex of a geometric shape (nodal lines) the sand creates. We initially plan on experimenting with an online frequency generator and a metal plate in order to see what how big of amplitudes we can make on the antinodal regions. Once we have found specific frequencies that resonate well with the plate, we hope to mix/record specific tones and develop it into an Arduino based electric xylophone. People will be able to play on the xylophone, creating their own beats that will create resonating geometric patterns in order for them to “see” what physical form their music takes on.

The Team

• Sudeep Raj
• Han Wang
• Li Gao

Objectives

---

• Finding several resonating frequencies of the plate since stable figures are obtained the best at these frequencies
  • Reference: Chladni’s law for vibrating plates by Rossing (Page 271)
• Achieving a consistent image will depend on the distribution of sand (or silica grains) spread on the plate since the higher density nodes will be providing the form we seek.
• Having at the least 5 unique sets of diametric and radial node patterns that are playable on the xylophone.
  • The higher the count on both diametric and radial nodes, the better
• At least 3 melody kits (specifically themed notes) the xylophone will be able to play
• During the demo, anyone should be able to play the xylophone and form images on their own (although we will prepare/practice some melodies that do create designs)

Challenges

---

Most of the hardware we will use can be purchased, but there are still many foreseen challenges we will encounter:

• We don’t know what are the resonant frequencies of our specific plate, so we will have to try find them using a predetermined range of frequencies from 20Hz to 2kHz (range is considered in order to stay safe and based on an article that ran a similar experiment)
• We may try different mediums (sands, silicon beads etc). They may get stuck on the center of speaker and cause damage.
• We may exceed our budget if our trials keep failing, so we need to form detailed plans on how we will run our experiments in order to prevent going over our budget
• Finding the most effective way to reuse and not waste our mediums
• Assembling all our equipment in a neat and organized way for demo
• Making sure each acrylic sheet attached to a Piezo Disc plays as programmed to

Budget

---

Speaker/Plate Setup

• 4 Ohm Sub (400 Watts RMS) (Walmart) ~ $17.38
• .063 Thick Aluminum Sheet (12 x 12) (Amazon) ~ $12.98
• Amp 38 W X 2 RMS @ 4 ohm, AB Class (BOSS) ~ $34.99
• Black Aquarium Sand 20lbs (Petco) ~ $11.39
• 3/4-in Common Birch Plywood (2 x 2 Ft) (Lowe's) ~ $10.80
• Ear Plugs (x3++) (Home Depot) ~ $4.00
• Wooden Rod (.625in Diameter and 2inch Length) ~ $3.28

Electric Xylophone

• Pink Plexi Glass (12 x 12) ~ $5.75
• Blue Plexi Glass (12 x 12) ~ $5.75
• Acrylic Cutting Tool (Home Depot) ~ $3.67
• USB Cable A-B ~ $1.49
• Piezo Discs (~1in Diameter) (Amazon) ~ $15.99

Owned

• Hot Glue Gun
• 10k Resistor
• 1M Ohm Resistors (x8)
• Arduino UNO
• Breadboard
• Solderless Jumper Wires
• DMM
• Cardboard Box (12in x 7in)
• Software:
  • Serial - MIDI Converter (SM) – MIDI (xylophone) data converter
  • Garageband (to read MIDI data and develop tunes)
  • Arduino

Est. Total

• ~$125

Schematics and Sketches

---

This is our visual-beats scheme. We first hit the xylophone, Piezo would receive the hit and convert pressure to voltage signal. The signal goes to Arduino, which would then convert signal to readable data of computer. Next, SM would converts data for Garageband and Garageband plays music through our amplifier/speaker system. Finally, the platform above the speaker vibrates and makes the unique pattern through sands!

This is how we gonna construct the xylophone. We put six 1.5*8 in acrylic plexiglass boards on the top of a 12*7 in box. Then we stick 6 piezo (1.1 in diameter) to the plexiglass boards.

On the bottom is a 3/4 in common birch plywood. We stick a 400w speaker(8 in diameter) to it and put a wooden cylinder (1 in diameter) on the top of the speaker. We then stick a 12 * 12, 0.063 in thick aluminum platform to the top of wooden cylinder.

Theory/Resources/Misc

---

The choices for the items under our budget are not arbitrary:

• The amplifier and subwoofer were chosen based on an article found on in the American Journal of Physics (AAPT). The article conducted an identical experiment and recommended using an amplifier that outputs at least 15 Watts and thus a sub that can handle such power
  • Article: Production of Chladni Figures on Vibrating Plates Using Continuous Excitation by Harald C. Jensen (Page 504)
• We concluded with a thickness of 0.063 for the Aluminum Sheet as as it satisfies the 6 assumptions presented in Kirchoff’s Plate Theory
  • Article: Resolving the formation of modern Chladni figures (A Letters Journal Exploring the Frontiers of Physics)
  • Text: [1] (Page 83-86)

Reproducibility of different shapes do not rely on the assembly of the setup:

• The only two factors needed to reproduce a shape found is by using the same frequency and the arbitrary boundary conditions created (Noted from Jensen's Article (Page 505))
  • We will not be experimenting with different boundary conditions and will only be using the center of the plate as the point of excitation (unfortunately, this will reduce the chances of us finding complex symmetrical patterns, but will not restrict us too far)

3D/2D Graphing Using Mathematica:

• We hope to use some of the theory found in the Resolving the formation of modern Chladni figures Article to compute some nice graphs explaining how our project works in relation to Kirchoff-Love's Equation !

Gantt Chart

---