Participant Entry / Exit Tones (see fn 01_52_06.jpg) should be disabled and greyed out if Meeting is set up with No Tone (see fn 03_32_20.jpg).
Because of the meeting No Tone configuration, Host controls to modify Entry and Exit Tone behavior are greyed out (see fn 03.33.32.jpg), therefore leaving the Host with no options to control such operations (Beeps) in the meeting. (Sometimes these Beeps get picked-up and fed into the meeting.)
The below pictures are included as reference to show where the mentioned controls are, not to show how they are to be set up; for that, see text above.
.Participant Entry / Exit Tone - attached picture fn 01_52_06.jpg
.Meeting Entry / Exit tone - attached picture fn 03_32_20.jpg
.Host options for Entry and Exit Tone - attached picture fn 03_33_32.jpg).
This request from customer Pega, pega.webex.com .