Shepard Scale Extravaganza Seth Simonds 5 th Grade Mrs. Wayne

Experimenting With Shepard Scales A Shepard Scale (sometimes called a Shepard Tone) is an audio illusion that tricks a person into thinking that the scale or tone is always either going up or that it is always going down. Question: What is the simplest way to make a Shepard Scale?

Penrose Stairs The Shepard Scale is very similar to an optical illusion called the Penrose Stairs. Pick a corner and pretend to either walk up or down. See how it goes on and on?

Ascending and Descending This is a famous drawing by M.C. Escher that shows one set of soldiers always walking up and another set of soldiers always walking down using a set of Penrose Stairs.

Observations and Hypothesis A website tool was used to produce a Shepard Scale The data for the notes and the volume of each note was copied into a table from the website. The website tool also allowed the music to be played faster or slower which had no affect on the audio illusion. The website tool also allowed the illusion to be played either ascending or descending and the illusion of going on and on worked for both. The Shepard Scale on the website was made using four scales. The hypothesis and experiment is to see if the effect of going on and on can be done only using two scales.

Materials and Procedures Materials –A website with a Shepard Scale tool –A music keyboard to play music scales –A computer program to generate a Shepard Scale Procedures –Used the website to learn how Shepard Scales work The website used 4 scales to produce the illusion –Played a music keyboard to learn music scales –Used a computer program called a Sequencer to make and manipulate a Shepard Scale with only two scales

This is the musical notation for the Shepard Scale. This was the scale that the website used to make the audio illusion. To create the illusion, just play these notes over and over again. It uses four ascending scales each starting with the C note. To make this presentation easier, only the ascending scales are shown but it can also work descending too. How the illusion works is that the Treble Clef (top) notes get softer as they are played and the Bass Clef (bottom) notes get louder as they are played. Each of the four scales changes its volume differently. See the chart below to see how the volume changes.

Note Scale 1 Volume Scale 2 Volume Scale 3 Volume Scale 4 VolumeVolume Total C C# D D# E F F# G G# A A# B

This is the musical notation for the Simpler Shepard Scale. The experiment was to see if using half the notes would also give the illusion of going up and up in tone. To create the illusion just play these notes over and over again. It works! The notes sound like they are always going up and up! Instead of using four scales to create the illusion, this created the illusion with only two scales. The same idea is used with the higher line of notes starting loud and getting softer while the lower line of notes starts soft and gets louder in volume. See the chart below to see how the volume changes.

NoteLower Pitched Scale 1Higher Pitched Scale 2Volume Total C0100 C# D D# E F F# G G# A A# B Scale 1 continues with the Scale 2 C note Scale 2 loops back down to the Scale 1 C note

Making a Shepard Scale It is pretty much impossible to play a true Shepard Scale on a single piano because to play different notes at different volumes is very hard. A computer or multiple keyboards have to be used to make the Shepard Scale because carefully controlling volume is needed to create the audio illusion.

Conclusion I found out that the easiest way to make a Shepard scale is by using two occurring notes that are both the same pitch but it does sound better with four notes. However the two scales are much easier to play and write and it still gives the sense of going on and on and on.

Data and Graphs

Scale Step 1

Scale Step 2

Scale Step 3

Scale Step 4

Scale Step 5

Scale Step 6

Scale Step 7

Scale Step 8

Scale Step 9

Scale Step 10

Scale Step 11

Scale Step 12

And Now Back to the Beginning