I can’t hear them and they can’t hear me

I just got the iPhone 11 literally for Christmas and it’s April and I try to FaceTime my friends and I can’t hear them and they can’t hear me...I also have an iPhone 6 that I tried it with but still I couldn’t hear them and they couldn’t hear me...we tried regular ft, Snapchat, WhatsApp, and airtime but we couldn’t hear each other. Please help me it’s been all normal until today.