Hear vs Listen

• Hear is a verb we use to talk about the ability to perceive sounds through the ears. These sounds may be unwanted or disturbing, for example: You can hear a dog barking and it's stopping you from sleeping.
  I can hear the air conditioning.
  I like to hear the birds in spring.

• Listen is a verb we use to say that we are paying attention to whatever we are hearing. It is often followed by the preposition 'to'.
  You should listen to your parents.
  I'm speaking to you! Listen to me.