If the student hit a drum in his bedroom, the sound wave would behave differently than if the drum was hit underwater. This is because when the drum is hit in his bedroom, the medium in which the sound waves travel through is air, which is much thinner and has more space in between the molecules than water, so the sound waves move faster. On the other hand, when the drum is hit underwater, the medium of water is more dense so the sound waves move slower through the water.
I hope this helps!