You may also want to try connecting the headphones to another medium to see if they work. If the sound continues, then you may already know that the problem is in the speakers or headphones. On the other hand, if you notice clear sound, it is a sign of a problem with its port.
Another suggestion is to check the wiring or the power supply. These extensions connect to several plugs (powering up to 10 devices), so you can stay connected. You may also want to switch to a different headphone jack. Whether you’re using the single input on your computer or using the front or rear input, you can switch it using your computer’s speaker jack.