Solve the problem of no sound in Ubuntu dual system

        As in the title, I installed the win10+Ubuntu18.04 dual system. In the Ubuntu system, no matter whether it is the earphone or the speaker, there is no sound, but in the win10 system, the sound can be output normally.

        After continuous searching and trying, I found that many methods on the Internet could not solve the problem successfully, and after installing pavucontrol, I found that there is only one item of HDA NVidia in the configuration column, and there is no second item of built-in audio as mentioned in other methods found. .

        Install pavucontrol command:

 sudo apt install pavucontrol

        After continuous exploration, it was found that it was because of the problem of the startup item grub, because the computer has a graphics card and cannot automatically start the built-in audio, so we need to modify the startup item.

        Terminal input command:

sudo gedit /etc/default/grub

        In the opened file, add a line of code:

GRUB_CMDLINE_LINUX_DEFAULT="snd_hda_intel.dmic_detect=0"

         Then save and exit, and then enter in the terminal:

sudo grub-mkconfig -o /boot/grub/grub.cfg

        Then restart the computer, and after running pavucontrol again at this time, you will find that the built-in audio item appears in the configuration list

        At this time, select the built-in audio as "Analog Stereo Duplex"

        The output device is selected as "Speaker". Through testing, it is found that as long as the earphone is plugged in, it will automatically change to the "Analog Headphone" mode, and there is no need to force the "Analog Headphone" mode to be selected.

        The problem is solved, and the ubuntu system has sound.