Rising growl effects like this became a staple of online editing because they solve a simple problem: how to make an off-screen threat feel present before anything is shown. Creators lifted the style from horror trailers, creature features and boss fight games, then reused the long build across memes, fan trailers and short horror clips. The slow swell works on soundboards and in short form video because viewers recognise the pattern instantly, even without an image, and expect a reveal, a chase or a scare to follow.