A student placed her ear on a student desk and listened to a second student tapping lightly on the desk. The experiment was repeated with same tapping but the first student keeps her ear 3 cm above the desk surface and the sounds were different. What is the best explanation for the different sounds?
a. The sound waves travel through the desk but not air
b. The sound waves travel slower through the air than the desk
c. The sound waves travel faster through the air than the desk
d. There is no explanation for the change in sound​