Here's why:
* "Listen" is a transitive verb. This means it usually requires a direct object – the thing or person being listened to.
* "To" functions as a preposition that introduces the object. It shows the direction or target of the listening action.
Examples:
* I am listening to music. (The object of the listening is "music").
* The teacher is listening to the students. (The object of the listening is "the students").
* She is listening to her heart. (The object of the listening is "her heart").
It's important to note:
* You can also use "listen" without "to" if you're talking about the act of listening itself, without specifying the object. For example, "The doctor listened carefully."
* "Listen to" is also used in the idiom "listen to someone's advice" or "listen to someone's reason".
Let me know if you have any further questions!