3.04 marine science honors, Sound in the Sea Lab—Stirring Up Sound

Objectives
demonstrate how the temperature of water affects the speed of sound
demonstrate how dissolved particulates and bubbles scatter sound

Hypothesis
Do the properties of water affect the way sound travels through it? Why or why not?

Materials
2 mugs (ceramic work best)
2 metal teaspoons
2 plastic straws
very hot (boiling) water (be careful as the water is very hot)
ice water
instant coffee

Procedures
Predict how sound may or may not change as the properties of water change. Write down your predictions. Here are some questions to get you started.
What adjectives do you use to describe sounds?
What do you know about the way sound travels through water?
Do things sound different underwater than they do in air?
Design an experiment to test the effects of a changing variable on the speed of sound. You will need to run three trials so that you can test three independent variables, one at a time: temperature (hot and cold water), a solution (the drink mix), and a disturbance (adding bubbles to the water). The dependent variable is the speed of sound, which you can measure by recording observations about the pitch of the sound. Since pitch is directly related to frequency, the higher the pitch of the sound, the higher the frequency (and speed) of the waves. Then, create a data table to record your observations while completing the experiment. Be sure to include a column in your data table to record time.
Use metal teaspoons to tap on the mugs to create sound. You may tap on the inside or bottom of the mug.
Fill the mugs three quarters of the way full with various temperatures or solutions of water. You may wish to mark a line on each mug to be sure the amounts of water remain consistent during the trials. You will repeat this process several times to investigate the following:
Investigate temperature to determine how sound differs between the mug containing hot water and the mug containing cold water. Consider how the temperature may change with time and how this may affect the sounds produced. You will need to tap for longer than one minute to observe a change.
Investigate a liquid solution and compare sound production in plain hot water vs. water that has instant coffee added to it. Continue to stir and produce sound for at least one minute after adding instant coffee, and make note of how the sound changes over time.
Investigate a disturbance in water by using the plastic straws to blow bubbles in the water and vary the force you use to blow air through the straw (this will change the size of the bubbles produced).

Conclusion Questions
How did you design your experiment? Why?
What properties of water did you investigate? Why?
What differences in sound between boiling water and ice water did you observe? Why?
How do you think temperature affects sound in the global ocean?
What differences in sound between still water and bubbling water did you observe? Why? Did you observe a change based on the size of the bubbles?
How do you think bubbles affect sound in the global ocean?
What differences in sound between plain water and coffee did you observe? Why? Did you observe a change over time?
What effects do you think climate change and warming oceans may have on the way sounds move through the ocean?
Sound speed is affected by the oceanographic variables of temperature, salinity, and pressure. We can look at the effect of each of these variables on the sound speed by focusing on one spot in the ocean. When oceanographers look at the change of an oceanographic variable with water depth, they call it a profile. Similar to the profile of your face, which gives a side view of your face, an oceanographic profile gives you a side view of the ocean at one location from top to bottom. It looks at how that characteristic of the ocean changes as you go from the sea surface straight down to the seafloor.

I do not understand the graph and how I am supposed to construct my response.
here is my work so far:

Objective: The purpose of this lab is to demonstrate how the temperature of water affects the speed of sound and to show how dissolved particulates and bubbles scatter sound.
Hypothesis: if the water in the mug is warm, then the frequency of sound will be higher.
Procedures:
Dependent variable: the speed of sound
Independent variable: The temperature of the water and types of solutions
Control variable: the amount of water, the same mug
Steps of the process:
1. Fill one mug with one cup of boiling water
2. Fill another mug with cold water
3. Fill the second to last mug with instant coffee and water
4. Fill the last mug with water and soap
5. Tap slightly on the inside of the mug
6. Record data
7. Repeat 3 times