Hearing the whistle is an event you can’t control. (Although I wish I could.) You are perceiving the sounds passively.
When you listen, or listen to something, it’s a conscious act.
If your teacher asks, Are you listening to me? when you don’t respond to a request for an answer, he/she is probably frustrated because it seems like you’re not paying attention. That is, you’re making a conscious effort not to listen, or you’re listening to something else that must be more important
If I ask you, Did you hear that? then maybe there was something off in the distance that sounded like a gunshot. It wasn’t me and it wasn’t you. But we both heard it.
The Cambridge Dictionary states it very well:
- Hearing is an event.
- Listening is an action.
Another example is:
Teacher is the object of the phrasal verb, listen to. In the same situation, a student might complain: I couldn’t hear the teacher because the bell was ringing.
The student can’t say, I couldn’t listen the teacher because the bell rang, and probably wouldn’t say, I couldn’t listen to the teacher because the bell rang.
Sometimes either listen (to) or hear can be used, depending on whether or not the speaker wants to emphasize the action or the event.
Do you have any questions about the difference between listen (to) and hear? Let me know in the comments.