Make a speaker inside a 9V battery

There are a lot of instructables stating how to make a speaker. Those speaker can be as tall as you and can be as small as your palm. But can you ever imagine that you can make a speaker inside a 9V battery. I know that it sounds weird but it’s actually possible. You can make a speaker with decent amount of loudness and intensity inside a 9V battery. The idea of making this tiny speaker came to me from a bunch of old batteries. I had a bunch of old dead batteries lying around and was trying to use them in some way or the other but finally ended up with throwing them in the trash. I took a 9V battery and started thinking what could I make with this thing. Suddenly I got an idea of making a speaker with a 9V battery and rather power the speaker with the battery, I decided to make a speaker inside the battery. Since I had all the required materials and tool, I started making the speaker.”