Please try this solution 

Potential Solutions: 

- 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.