There can be many causes for not being able to hear participants or they you. It could be the audio feed or issues with the microphone.
Something worth trying…
If you have a pair of earbuds from your Smartphone with a plug with three rings for the laptop, this is a helpful tool to help with audio. This means it can handle audio and a microphone. Note that the microphone is also built in to the headset.
Test the earbuds before the session by clicking on the Microphone button at the bottom left-hand corner of the Zoom screen. Select “Test Speaker and Microphone.”
Benefits: The person using the earbuds can hear better. The people on the other end can hear you better because of the microphone built into the earbuds.
WongTechTips 