You want to study the ability of students to talk at a normal tone while listening to loud music with their MP3 player headphones. You measure how loud a student talks normally, then you measure how loud the student talks while listening music with his or her MP3 player headphones. The control group is students who do not regularly use an MP3 player. The experimental group is students who regularly use an MP3 player. Part a: Is the study experimental or observational? Part b: Explain your reasoning