To fix Audio issues on your system follow the below steps.

Step1: First Ensure all the Drivers are up to date & Check

• Install Dell SupportAssist if you have not installed 
• After installing, Open SupportAssist & Click on “Run Now” under Get Drivers & Downloads
• Restart the system & Check if it is working fine

Check the video.

Step 2: Run the Audio Troubleshooter.

• Right Click on the Speaker Icon & Click on “Troubleshoot”
• Click on “Troubleshoot Sound Problems”
• Follow the on-screen instructions & check

Check the video.

Step 3: If the above steps fails:

• Go to device manager and look for Realtek Audio driver
• Uninstall it and ensure to check to delete the software.
• Install the Audio driver again from our site
• Once installed, Right-click on Start and go to task manager
• Click on startup and enable Waves Maxxaudio

Check the video.