When mic picks up the sound signal from the speaker in the same room, echo is generated on the line. Headphones can prevent this and is highly recommended for all participants in the session. Anyone without headphones should ensure that "echo cancellation" is ON.
The downside of ECHO CANCELLATION is that the processing required to cancel echo will result in less than ideal sound quality. For best audio recording experience, make sure that all participants are wearing headphones and then turn ECHO CANCELLATION OFF for everyone.
For safety reasons, ECHO CANCELLATION is ON for all participants when they join Boomcaster sessions. Guests are offered an opportunity to change this setting, when they join. But hosts can change this setting any time during the session for any participant.