Physics Project: Investigating Sound Attenuation

[fisicasound]

Sound attenuation

for my physics project I decided to investigate sound attenuation effect, for my equipment I’m using a speaker with a signal generator and at the other end a microphone with an oscilloscope...the sound generator and receiver were placed inside a tube which was well insulated to prevent the apparatus resonance(but i still get a resonance effect and I don’t know if it will affect my results)...also the apparatus is designed so I could insert different materials and different thicknesses in between the receiver and speaker

I was wondering if anyone could answer the following questions.

1. to show my results in dB i must find the sound intensity in W/m^-2...is it the same as the peak to peak voltage readings in my oscilloscope

2. What type of materials should I be looking for that can be easily accessible?
I was thinking of polystyrene, also what properties in a material make it good for sound insulation?

3. To plot graphs I was thinking of using the equation lnI= lnIo - μx where μ is the materials coefficient of attenuation and x is the thickness of the insulation...for the graph I was advised to vary x keeping the frequency constant but I don’t really know what frequency I will chose since humans have can hear a really big range of frequencies.. will the second graph for the same material vary μ as I change frequency

if u have any suggestions for any other experiment suggesting sound attenuation ill be glad to hear it

Thanks

 

[Astronuc]

One could try a metal bar, a wooden rod, and polystyrene foam or polyethylene.

One could also try different frequencies of low, med and high in the range of human hearing to see what the difference, if any, in attentuation might be.

Sound proofing tends to be soft material vs hard material.

 

[m2003]

for sharing your physics project with us! It sounds like you have a well-designed experiment to investigate sound attenuation. To answer your questions:

1. To show your results in decibels (dB), you will need to calculate the sound intensity in W/m^-2. This can be done by using the peak to peak voltage readings on your oscilloscope, as long as you know the conversion factor between voltage and sound intensity for your specific equipment. This conversion factor may vary depending on the sensitivity of your microphone and the power of your speaker.

2. The type of materials you should be looking for to use in your experiment are ones that are good at reducing sound transmission, or have a high sound transmission loss (STL) value. This can include materials such as foam, rubber, or even cardboard. The properties that make a material good for sound insulation are its density, stiffness, and thickness. Generally, denser and thicker materials will have a higher STL value.

3. Your equation for plotting graphs seems like a good approach. To vary the material's coefficient of attenuation (μ), you can change the type of material you are using. However, for the second graph, you should still keep the frequency constant. This will allow you to see how the material's attenuation coefficient changes at different frequencies.

As for suggestions for other experiments, you could try investigating the effect of different shapes or sizes of the insulation material on sound attenuation. You could also try comparing the sound attenuation of different materials at different frequencies to see if there are any patterns or trends. Good luck with your project!