I wasn't sure if this was the right place to post this, but it looked close enough. I have a younger sister who has to do a project for an annual science fair. My mother signed her up for a project that involves measuring how well sound travels through solids, liquids and gases. Because I have an interest in electronics, she figured that I would be able to come up with some mechanism of accurately measuring, in her words, "How loud the sound will be" coming through the different materials. First off, it seems like measuring how loud the sound will be might not be the best thing to base an experiment on. And if I'm correct in assuming that such an experiment would not be useful, I need to know if there is a good alternative. What is the best way to make the measurements she would need, and if necessary, what sort of device might I need to build? Thanks in advance.