There is no sound when the monitor is connected using the HDMI interface, because the HDMI interface is an interface that contains both audio + video signals. When the computer's HDMI interface is used, the system will default from the HDMI device output sound signal, and at this time if the HDMI device does not have sound playback function (such as the author of the speaker's HDMI LCD monitor), the computer has no sound!
Solutions
The solution is actually very simple, there are some statements on the Internet so complex requires an external conversion line. Because this is the scope of software problems, to solve the computer failure is also in the first soft after the principle of hard. Later, the Discovery Device Manager in the "sound, video and game controller" column has two devices, respectively, "AMD High Definition Audio" (more with the use of video cards and processors, the previous AMD may be Intel or Nvidia) and "high Definition Audio "as shown in the following figure:
All we have to do is disable it with AMD High Definition Audio (which may not be the AMD word on your computer, which will be different for your computer to provide a display chip) and then resolve the problem of no sound after the computer is connected to the HDMI display. If you are unsure which one or what the author describes, you can disable the test and use the elimination method to solve the problem. Disable the method: Right-click on the device and select "Disable", as shown in the figure below. Now the author's subwoofer will not be wasted in vain.