On voice calls, the volume of my friends voice is so reduced I can't hear them.

This morning, I was talking with friends on a voice call. After a few hours, I left and rejoined the call. When I did that, the volume of voices was reduced by so much I couldn't hear anything. I turned the volume up from 4 (the volume I use on my PC) to 100. At this point, I almost couldn't hear them talking.

If you got anything that could help, please write it down in the comment.