When a balloon pops, what is actually creating the sound I hear?
In: Physics
Expanding air.
Sound is just vibrating molecules. When you play music from speakers, the speakers vibrate the air and those vibrations get picked up by our ears. Stronger vibrations sound louder, and smaller ones are quieter.
When a balloon pops, all of the air inside is suddenly free to expand. So it does, instantly and with quite a bit of force since it was at a lot higher pressure than the outside air. Our ears perceive this big pressure wave as a bang.
Your ears perceive pressure changes in the air as sound. The noise generated by something at a distance is commonly called sound pressure level. When a balloon pops it is imparting its pressure into the air outside of the balloon, creating a change in pressure – your ears then sense this and you hear a loud pop.
Think of air as a spring that goes in all directions – the air in the balloon is compressed, while the air outside the balloon is not (well, it’s less compressed). When the rubber breaks, the inside spring expands and causes the outside springs to compress as it does so. This will oscillate a bit until equilibrium has been settled upon, and these oscillations in the air are what we perceive as sound.
The echo plays a big role in that process. Take a look at this video of a balloon popped in an anechoic chamber: [https://www.youtube.com/watch?v=MyP7i1B_QNk](https://www.youtube.com/watch?v=MyP7i1B_QNk)
In short: Air.
All sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
When someone talks, they move air that your ear feels as sound.
A balloon is pressurized air. When you pop it that pressure propagates outward in a wave, that your feels as sound.
Think of it as dumping a bucket of water in a lake and watching the waves spread outward.
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