system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it that some farts sound like thunderclaps, while others sound like the air is being slowly released from a balloon? And then, there are the silent ones that usually smell worse than the audible ones. I need some help understanding the science of flatulence.
gpt
Think of your ass as your mouth for a second. Your lips are now your ass cheeks.  

Open your mouth (lips) and blow air out of your mouth.  Here's the "air out of balloon" sound.  Now close your mouth and blow (force) air out - you may have to lick your lips for added sweaty ass lube.  The lips will vibrate and create the general fart noise.

Take those thoughts/feelings to your ass, and this is what happens to your ass cheeks when air passes past them. Length and strength of the fart will alter the sound in volume and type.