Okay kiddo, so you know when someone is speaking and their voice sounds really scratchy and rough? That’s kind of like what “spiritus asper” means. It’s a fancy way of talking about a type of sound or voice that is harsh and rough.
Imagine if you tried to talk after you took a big gulp of water and you couldn’t quite get the words out smoothly - that’s kind of like spiritus asper. It’s caused by things like throat irritation, allergies or infections. Sometimes people can even intentionally make their voice sound rough or gravelly, like if they want to sound tough or spooky.
So, basically, spiritus asper is just a way of describing a voice or sound that isn’t very smooth or gentle, but is instead scratchy and rough.