You may be experiencing any of the following audio issues:

• Cracking or popping sound from the external speakers
• Sound quality issues during phone calls
• No sound coming from one of the external speakers

Follow these steps to help you resolve the issue:

1. Lower the volume slightly.
2. Use a different audio device (different headphones, external speakers), to see if the issue continues to occur; check the audio file or play another song and see if it's consistent.
3. Turn off the NFC function, as it can sometimes interfere with speakers or headphones.
4. Close background applications  by tapping the Recent Apps key, and then swiping the application thumbnails off the screen to close them.
5. Remove signal interference in areas with multiple Wi-Fi networks or radio transmission, by moving away from possible sources of radio signals.