<span>At an instant when the displacement is equal to a/2,
Potential energy U = 1/2ka(square) where a is displacement.
when a= a/2
U = 1/4ka(square)
U = E/4
Potential Energy = 1/4 Total energy</span>
I think the closest possible answer to this question is The air density increases and decreases repeatedly before returning to normal.Thank you for your question. Please don't hesitate to ask in Brainly your queries.