Question

Suspend a sheet of paper so that the top edge of the paper is fixed and the bottom edge is free to move. You could tape the top edge of the paper to the edge of a table, for example.

Gently blow air near the edge of the bottom of the sheet and note how the sheet moves.

Speak softly and then louder such that the sounds hit the edge of the bottom of the paper, and note how the sheet moves.

Interpret the results.

Answer 1

suspending a sheet of paper by taping the top edge to a surface and letting the bottom edge hang freely
then, when blown at, the sheet moves chaotically, but it does respond to changes in air pressure around it

now, when, insted of blowing wind onto the paper, we speak near the paper, the paper gain shows the similialr kind of movement, but this is very small in amplitude
this means that when sound travels in air, there are pressure changes in air
also, these pressure changes are very small as compared to pressure changes when we blow at the paper and that is why the amplitude of motion of the paper is low when we speak

again, when we speak louder, the amolitude of motion of the paper is higher as compared to when we speak at lower amplitude
hence this meansa loudness is proportional to the pressure changes that occur in its propogation