Science Project to show what matter does sound travel best (farthest) through

[reshmamohindra]

My first grader daughter has chosen to do a science project about sound and what matter does sound travel best through. I helped her define 'best" as what can you hear farthest. We are struggling on how to measure this underwater. We plan to use the swimming pool and stand at increasing distance from the source of sound (on a recorded device to control volume). I was hoping the school would have an underwater decibel meter to measure the sound but they don't. I could use a decibel meter app on my iphone but don't plan on submerging it in water. Any ideas?

[eedoherty]

Hi there,

I've just looked back through a few posts on this site with a similar problem, and it looks like most ended up changing the scope of their experiment slightly because of the cost of an underwater decibel meter.

I like the idea about traveling sound, perhaps you could modify it slightly so it is more test-able?

One example of a project on this site that is similar is "Can you hear sound in outer space?". This project uses a a decreasing density of air (by making a vacuum inside of a flask) to test how the amount of air affects sound intensity. It gets at a similar goal to your original project but is more easily testable.

https://www.sciencebuddies.org/science- ... ound-waves

Check it out and let me know what you think!

Erin

[reshmamohindra]

Hi Erin, you link was very helpful. Thanks so much. Do you think we could show the intensity of sound through water by filling the beaker with water and then recording? And through gas by repeating with just plain air. Both air and water would be without heating the flask.

[eedoherty]

Hi there,

Yes I don't see why that wouldn't work! Sounds like a great way to adapt that project to your original idea. Let me know if you have any more questions!

-Erin

[reshmamohindra]

Hi Erin, one of the steps is as below:
As soon as the stopper is safely and tightly secured in the flask, press the record button on the Science Journal app and place the flask on top of your phone
The flask will be hot. Is it safe to put on the phone?

[eedoherty]

Hi there,

You are right that in the procedure the flask would be hot when it is first placed on the phone, and then cools to room temperature as the trial completes. I can't speak to having done this experiment personally, but projects on this site have been tested and edited, so this would have been safely attempted in the past. Based on that I would say it should be safe, I know that iPhones will alert you on the screen if they are above a safe operating temperature, so you could always watch for this if you are concerned.

Hope that helps!

Erin

[reshmamohindra]

Hi Erin
Figured we would do the easier part of the experiment first (air, water, solid). Interestingly, the results were opposite of what should have happened. The beeper which had a free standing (outside the beaker) sound intensity of 73, recorded the following averages in the beaker (repeated each 2-3 times):
Filled with Air: 54
Filled with Solids (we used dry beans filled up to about 1 cm below the buzzer): 30
Filled with water (filled up to about 1 cm below the buzzer ): 34
Filled with water (filled up to about 5 cm below the buzzer ): 38

I am assuming our set up of the experiment above is faulty. Please let me know your thoughts.

Also, the buzzer keeps losing contact with the battery when I try the steam/vacuum experiment (using duct tape). I will try to find a gaffer tape tomorrow.

Regards
Reshma

[eedoherty]

Hi Reshma,

So sorry for the delay in getting back to you. Did the use of gaffer tape in your set up yield different results?

The results are interesting. If you are using the mean of the experiments, maybe it is better to look at the whole range (min to max) that you record? Perhaps the mean is not the best representation of the results for this experiment. If that doesn't help, let me know and we can talk more about your setup and see what might be going wrong.

Best,

Erin

[reshmamohindra]

Hi Erin

Thank you for the follow up. The gaffer tape worked great for the vacuum portion of the test but did not really make a difference for the solid and liquid portion. BTW, we ended up causing the battery to melt eventually since it must have touched the hot beaker! But we had enough readings. Now we know

Unfortunately, the project was due on the 9th of March. Since we were running out of time, we compromised and went back to a 2 pronged approach.
1. Compare sound transmission in air vs solid using the string telephone approach
2. Compare sound transmission in air vs vacuum using the beaker experiment "can your hear sounds in space".
While it was not ideal, it allowed her to explore the concept and be able to show the differences through various states.

I would love to eventually try the original experiment again just so she can see the concept with only 1 variable (the state) being changed without the pressure of time and school reports. Would love any other ideas from you.

Thanks again!

Reshma