Most common cause of echo or audio feedback is when multiple audio devices, which are connected to the same meeting, are either too close to each other or too loud. Make sure only one audio device is active when working from a shared (conference) room or desk. You can mute your microphone by clicking the microphone icon in the meeting’s taskbar.
Also check if you, or any of the other participants, have two open connections to the meeting. This would cause the microphone to pick up the sound and create echo or audio feedback.
If muting or turning down the volume does not solve the issue, check your hardware. Possible hardware related causes can include bad microphones or malfunctioning echo- or noise-cancelling capabilities/settings of the device. Refer to the manufacturer’s website for additional user guides or troubleshooting help.