1. Check if the sound distortion is present in both your headphones and speakers.

2. Make sure your smartphone is sufficiently charged and hasn’t dropped below a certain voltage level.

3. Reset your phone by turning it off and back on again.

4. Clear your phone's cache data.

5. Play some music and see if the distortion persists.

6. Check to see if there are any loose connections or worn out parts in your phone's audio equipment.

7. If the distortion is still present, take your phone to a trained technician for a closer inspection.