
String Length and Musical Notes
Hard
Can a single equation predict every note on a musical scale? A monochord is a one-string instrument with one fixed bridge and a movable fret. You pluck the open string and measure its frequency with a microphone sensor.
You then search for a multiplier that produces all 13 half-steps in one octave. Starting with a 60 cm string, you need a ratio that reaches 30 cm after 12 multiplications. That ratio turns out to be about 0.9439. You move the fret to each calculated length and check the frequency.
The measured notes match the predicted ones every time. The pattern holds across three octaves and more than ten trials each. You also find that notes one octave apart always have a 2:1 frequency ratio.
Hypothesis
The hypothesis is that different lengths of a 60cm string, where the fret is placed, will produce speculated notes and will fit in a mathematical equation.
Method & Materials
You will use a monochord, a single string with one fixed bridge and a movable fret, to measure the frequency of the notes. You will then use mathematical equations to calculate the length of the string for each note.
You will need a monochord, a single string with one fixed bridge and a movable fret, a CBL, a microphone, a calculator, the program SOUND and FREQ, and an intellitouch tuner.
Results
The results of this project showed that music and math have a lot in common. It was found that the string length for each note, in any given octave, fits in a geometric sequence. It was also found that two notes that are one octave apart, the string lengths are in a ratio of 1:1/2. The note sol, in all the octaves is 2/3 of the length of the string.
Why do this project?
This science project is interesting and unique because it shows the mathematical relation between music notes and equations.
Also Consider
Experiment variations to consider include using different musical instruments and exploring different mathematical equations.
Full project details
Additional information and source material for this project are available below.Related video
These videos explain the science behind this project and demonstrate key concepts used in the experiment.
Discover the intriguing connection between math and music, as Eugenia Cheng, mathematician and concert pianist, delves into the fascinating story of how mathematicians' advancements in calculating the 12th root of two enabled Bach to write music in every key. Prepare to be awed by the intricate relationship between these two seemingly unrelated disciplines.
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