Here are a few things that may help resolve the sound issue:

1. Check you have the right audio device selected – check the relevant audio input/output settings of your computer, be it headset, speakers, etc. and ensure that it is correctly selected in Teams as the audio device.
2. Check volume settings – you may want to increase the volume settings on both your computer and the Teams app.
3. Test in another app – use an external audio app like iTunes to check that sound is working in general.
4. Check your mute settings – make sure your computer and the Teams app are not muted or on do not disturb.
5. Reset your audio settings – if nothing else works, try resetting the audio settings on your computer and in the Teams app.