describe an experiment to show that sound cannot pass through vacuum?

We can consider a simple experiment in which we an electric bell in a closed glass jar. We connect the jar to an air pump which can suction out all the air from inside the glass chamber. In the beginning, we can hear the sound of the bell ringing but as air is slowly sucked out the sound gets lower. Once all the air is sucked out, a vacuum is created and the sound of the bell can no longer be heard.

Thus, we have proved that sound does not travel through vacuum.