Singing Goblets: Measuring Sound Frequencies from Glass Goblets

Overview

Objectives/Goals The objective is to test the hypothesis that greater liquid volumes and thicker liquids make a glass goblet resonate at a lower frequency. Also, to determine what effect size and/or shape of goblet has on frequency. Methods/Materials I used a KORG Chromatic Tuner CA-30 to measure and record pitches of a small and big glass goblet filled at different volumes with either water, vegetable oil, or molasses. I repeated all trials. I used the formula: f(2) = f(1)* 2^(x/1200), where f(2) represents the sound frequency in Hertz, f(1) the frequency of the closest semitone, and x the number of cents (a unit of pitch based on the equal tempered scale) away from the closest semitone, to convert the recorded pitches to frequencies. Results Greater liquid volumes produce lower frequencies than goblets filled with less liquid. Oil produced higher frequencies than water, molasses lower than water, and the smaller goblet produced frequencies lower than the larger goblet. Results were very consistent and repeatable. Conclusions/Discussion My hypothesis that as more liquid is added the frequency gets lower was correct. The size and/or shape of the glass also influenced the pitch along with the liquid's density. Liquid volume had a greater effect on frequency than liquid density, however.

Competition history

• CSEF 2005 Physics & Astronomy · Entry J1511

Resources

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