I had used 2 separate devices for a video call. Desktop for video and audio and phone for recording, since the desktop microphone is not working properly. Unfortunately when I started speaking, my first few words got echoed perpetually, and my following words were ignored. What is the reason behind this phenomenon?
When you spoke the first few words, the microphone recorded it and the audio was played through the desktop's speakers. Since the audio output of the desktop would be louder than your voice, the microphone picked up that audio signal. This recorded audio would be played on the desktop again, and it would get recorded by the microphone. This forms a closed loop feedback system, and the oscillations are sustained since the desktop amplifies it every time.