This article lists several solutions Epson Projector has no sound for Epson fans. You can try these methods accordingly if you have no idea of the failure cause.
You can firstly adjust the volume settings.
Press [Mute] button at the middle of the remote control to resume audio.
Pull the audio cable out and plug in again to avoid improper connection.
Make sure all connected audio cables are labeled as “No Resistance”.
If you are using the USB Display function, turn on the Output audio from the projector setting in the Epson USB Display Settings program on your computer.
Make sure your Mac supports audio through the HDMI port if your projector are connected to Mac . If not, you need to connect an audio cable.