By default Zoom Meetings use a very compressed algorithm to stream the audio and video signals to participants. Clear audio is critical in a learning situation -- every word is important. The compressed audio sometimes comes across as a muffled. unintelligible  word or two. Meeting settings can be adjusted to make the audio clear. In my limited observations, when the Original Sound is ON there may be more background noise in the room, but the speaker's voice is clear.

These screen shots were taken using Zoom Version 5.5.4

First, Open the Audio Settings on the Audio (microphone) icon in the Zoom Meetings. 

On a PC, click Advanced to open the Advanced audio settings (On a Mac there is no Advanced link, see image below)

Check the box to enable the ability to Enable Original Sound in a meeting. This option only affects the microphone on the speaker's computer. 

In the meeting there is an option in the top left of the screen to toggle Turn On Original Sound. 

 

Mac Settings for Audio options: