1. Check In-Game Audio Settings
From the main menu, go to [Settings] → [Audio].
Make sure all Volume Bars are set to maximum (Max) or an audible level.
2. Test Different Audio Devices
If using headphones, switch to speakers and check if the sound plays normally.
Conversely, if using speakers, try switching to headphones to see if the issue persists.
3. Check Default Output Device
Some audio devices may not be recognized properly depending on your Windows default sound output settings.
From the Windows taskbar, right-click the sound icon and select [Choose Output Device].
Confirm that Hi-Fi RUSH is using the correct audio device.