* The amount of gas: More gas usually equals a louder sound.
* The speed of the gas release: Faster release leads to a louder noise.
* The composition of the gas: Different types of gas produce different sounds.
* The anatomy of their digestive tract: The shape and size of the intestines can influence the sound.
So, while it's a common misconception that they always pass silent gas, it's not necessarily true. They can be just as gassy as we are, and sometimes, those toots can be quite loud!