To resolve this, please try the following:
Plug your earphones into a different device (phones, music player, etc).
NOTE: Make sure your earphones are completely plugged into the jack.
If the audio from the new device is fine, move the cable gently near the jack and also near the earphones.
If the sounds cuts out or you hear audio interference, then the cable is likely to be damaged. You will need consult Knowledge Base article 12278 for instructions on contacting Logitech Technical Support.