Another possibility is that the fanfic is in a format that is not compatible with the device's audio capabilities. Some file types might not be recognized by the media player, resulting in no sound even if Ben's hearing is fine and the device is working properly.
Perhaps 'Ben' is a character in a particular context and within that world, he has some sort of condition that makes it so he can't hear fanfic. It could also be a very specific in - joke or reference within a particular fandom where 'Ben' is known and his inability to hear fanfic has a special meaning related to the storylines or relationships within that fandom.
It was a pity to not listen to all the books, but not all novels could not be heard. Some novels could be missed for various reasons, such as the author's sudden death, not listening to the copyright in time after it was sold, or being adapted into other forms of works, etc.
Even in complete novels, we can't guarantee that we can hear every plot because some novels may have many chapters and we may only hear a part of them. In addition, we may not be able to listen to all of them due to personal interest, work, or other reasons.
Although listening to the book is not entirely a pity, we can still appreciate the wonderful plot and characters in the novel and understand the story in depth by reading the complete version.
Ben 110 can be developed by giving him new challenges related to the Highbreed. For example, he could face a Highbreed villain who has a power that nullifies Ben's alien forms. This would force him to rely on his human intelligence and resourcefulness. He could also develop his character by learning about the Highbreed's language and communication methods, which would show his adaptability.
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.
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?