I can not hear voice chat in overwatch


i have been playing overwatch for many years now and i have never had a use for voice chat but since now i am playing more competative some people are talking in voice chat and i decided to join them. So my problem is that if i dont have my headset in i can hear what the people are saying but when i plug my headset in then all i can see is the icon that they are talking. please help me try and fix this.