Please try this solution
- Adjust the volume to max volume to see if there is any sound at all.
- Make sure Soundcroe R500 is paired successfully to your device.
- If the sound issue occurs when answering a call, make sure you also select the "Headset" sound option when answering the call. Some phones automatically switch call sound to the phone itself and must be manually adjusted.
- Clean the mesh on the earbuds using a cotton bud and a little alcohol-based disinfectant.