Science Buddies: "Ask an Expert"

I have a couple questions regarding the science buddies experiment "Less Cowbell! The Unconstrained Truth About Constrained-Layer Damping" found at https://www.sciencebuddies.org/science- ... y&from=TSW

The procedure mentions the following "Advanced students may want to try measuring frequency response instead. To do this, use the software to calculate the sound amplitude versus frequency. Then pick the highest frequency peak amplitude above 1KHz for comparison with and without damping. Try to pick a peak that you think is a natural frequency of the pan."

I have installed the Audacity software but I don't understand how to use it to measure the "frequency response". I really don't understand much of this paragraph and could use some assistance. My questions:

• What does "the highest frequency peak amplitude" mean?

• How would one determine the natural frequency of the pan?

• Can someone provide more details or step by step instructions on how to measure the frequency response with Audacity?

Any helps would be greatly appreciated. Thanks!

Hi pdlabelle,

It looks like you've selected a very interesting experiment. I understand your questions...let me take them one at a time. I have also downloaded the Audacity software to give you guidance in looking at the data.

Q1) What does the "highest frequency peak amplitude" mean?
A) Objects can vibrate at one or a set of frequency ranges. A flute vibrates at only one frequency, string instruments (i.e. guitar) have mathematical relationships between frequency (harmonics) and other objects such as a dropped pencil have very complex and nonmathmatical frequencies. See http://www.physicsclassroom.com/class/sound/U11L4a.cfm
In this experiment, you are being asked to filter the sound wave resulting from the clanking pan and only focus on the peak amplitude above 1KHZ. Therefore, disegard amplitudes below 1KHZ. In the audacity software, you'll record your sound wave. You'll highlight the sound wave by clicking and holding the left mouse button and then dragging over to the right (should highlight in grey). Next, go to the pull down menu and click "Analyze" and then click "Plot Spectrum". This will pull up a seperate window with a plot of sound amplitude (db or decibels) on the Y axis and frequency on the x axis. Find the peak sound level above 1KHZ.

Q2) How would one determine the natural frequency of the pan?
A) As mentioned above and talked about in the above link; objects can have one or a set of frequencies at which they vibrate. The pan, having a complex sound wave will most likely vibrate over a series of frequencies. The goal of your experiment is to observe how adding a sound damper changes the amplitude and or frequencies at which the pan vibrates.

I hope this help!

Best of Luck,

Marc

Marc - Your answers were quite helpful. Thank you for taking the time to help!