The reason might be for adding drama or creating a special situation for the story. Maybe it's a way to make us feel sympathy for the old man or to lead to some important plot development.
Maybe the old man has some health problems in the cartoon's story. That could explain it.
It could be that the cartoon creators wanted to show a disadvantaged character. Or perhaps there was an accident or illness that affected his senses.
Maybe the volume of the cartoon is too low or the old man has hearing problems.
It could be that the man's eyes have some problem or he's in a part of the cave where visibility is extremely limited. Also, there might be something blocking his view.
Maybe they got deleted or moved to a different folder.
The manga tells a poignant story where the main characters can't see and can't hear but find love. It delves into their journey of connection and the obstacles they overcome together.
It could be that the source of the story has some technical glitch, or there's interference in the audio transmission. Have you tried using a different device or checking the connection?
Maybe there's a problem with your device or the app you're using. Check if the volume is turned up and if the app is updated.
Maybe it's because fanfiction exists in a written or digital form and doesn't have an audible component by default. Harry, like any normal person, can't just magically hear the words of fanfiction unless it's been read out loud to him or turned into an audiobook.
Perhaps you don't have the right app or software installed to access the stories. Make sure you have the necessary tools and that they are up to date.
Maybe there's a problem with your device's audio settings or the source of the stories has some technical glitch.
Maybe there's a problem with your device's audio settings. Check if the volume is turned up and if the speakers or headphones are working properly.