I'm a native English speaker, and "to listen to" is slightly different than "to hear"... Let me explain further:
to hear = to merely understand that there is noise: ...My girlfriend hears me in the kitchen, but she can't understand my words. She just hears mumbling.
to listen to = to understand that there is noise AND to understand exactly what is being said: ...My mother listens to me when I'm sad and responds with love.
To review: use "listen" when you can fully understand the noise and are engaging with it (I listen to music in my room) and use "hear" when you know there's noise, but you can't necessarily collect every detail (Do you hear dad lifting weights downstairs?)
Why is "listen to the boy" incorrect? In English, if you say that, it implies "you" and the "you" is not necessary.
Here I typed what I knew the answer to be, not what I heard. Perhaps it is my hearing, but it sounded again and again when spoken regularly: kota. Oh well. I try not to listen to the slow speaking.