Place the tube to the ear of a friend and speak ( not too loudly ) into the tube, can they hear what you are saying?
Try again, but this time fill the tube with the bubble wrap first, try to speak at the same volume you did before, can they still hear you?
Do the same thing with all your different materials.
Can you design a table to record your results? Which material muffles the sound the most?
Things to think about
Do you know why you need to speak at the same volume each time?
This is because when we experiment, usually we have one variable ( one condition we change ) and everything else must stay constant to test each variable fairly.
If you wanted to try speaking at different volumes you’d need to keep the material inside the tube constant.
Other things to try
Can you use different length tubes?
How else can you block sound? What if you cover your ears with your hands? Is it different with your fingers open and closed.
Great for Key stage 2
Obtaining and presenting evidence
Original article and pictures take http://www.science-sparks.com/2014/04/28/properties-materials-muffling-sound/ site