我升级到 Ubuntu 18.04，声音消失了，并显示了臭名昭著的“虚拟输出”，我以为问题出在 alsa 和 pulseaudio 上，所以我删除了它们并重新安装它们，但这并没有解决问题。我尝试了命令，aplay -l
输出是：aplay: device_list:270: no soundcards found..
我试过了lspci，输出是：
00:00.0 Host bridge: Intel Corporation Skylake Host Bridge/DRAM Registers (rev 08)
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 520 (rev 07)
00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21)
00:14.2 Signal processing controller: Intel Corporation Sunrise Point-LP Thermal subsystem (rev 21)
00:15.0 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #0 (rev 21)
00:15.1 Signal processing controller: Intel Corporation Sunrise Point-LP Serial IO I2C Controller #1 (rev 21)
00:16.0 Communication controller: Intel Corporation Sunrise Point-LP CSME HECI #1 (rev 21)
00:17.0 SATA controller: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode] (rev 21)
00:1c.0 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #5 (rev f1)
00:1c.5 PCI bridge: Intel Corporation Sunrise Point-LP PCI Express Root Port #6 (rev f1)
00:1f.0 ISA bridge: Intel Corporation Sunrise Point-LP LPC Controller (rev 21)
00:1f.2 Memory controller: Intel Corporation Sunrise Point-LP PMC (rev 21)
00:1f.4 SMBus: Intel Corporation Sunrise Point-LP SMBus (rev 21)
01:00.0 Network controller: Intel Corporation Wireless 3160 (rev 83)
02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8101/2/6E PCI Express Fast/Gigabit Ethernet controller (rev 07)
如您所见，没有音频设备。
我运行了 alsa-info 脚本https://gist.github.com/craftyjon/902247 输出结果如下：
upload=true&script=true&cardinfo=
!!################################
!!ALSA Information Script v 0.4.64
!!################################
> !!Script ran on: Sat May 5 14:11:34 UTC 2018
> !!Linux Distribution
!!------------------
> Ubuntu 18.04 LTS \n \l DISTRIB_ID=Ubuntu DISTRIB_DESCRIPTION="Ubuntu 18.04 LTS" NAME="Ubuntu" ID=ubuntu ID_LIKE=debian PRETTY_NAME="Ubuntu 18.04 LTS" HOME_URL="https://www.ubuntu.com/" SUPPORT_URL="https://help.ubuntu.com/" BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/" PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy" UBUNTU_CODENAME=bionic
> !!DMI Information
!!---------------
> Manufacturer: Dell Inc.
Product Name: Inspiron 5559
Product Version:
Firmware Version: 1.1.6
Board Vendor: Dell Inc.
Board Name: 04D1V1
> !!ACPI Device Status Information
!!---------------
> /sys/bus/acpi/devices/ACPI0003:00/status 15
/sys/bus/acpi/devices/ACPI000C:00/status 15
/sys/bus/acpi/devices/DELLABCE:00/status 15
/sys/bus/acpi/devices/DLLC6B2:00/status 15
/sys/bus/acpi/devices/DLLK06B2:00/status 15
/sys/bus/acpi/devices/INT33A1:00/status 15
/sys/bus/acpi/devices/INT33D0:00/status 15
/sys/bus/acpi/devices/INT340E:00/status 15
/sys/bus/acpi/devices/INT344B:00/status 15
/sys/bus/acpi/devices/INT3F0D:00/status 15
/sys/bus/acpi/devices/LNXPOWER:00/status 1
/sys/bus/acpi/devices/LNXPOWER:01/status 1
/sys/bus/acpi/devices/LNXPOWER:02/status 1
/sys/bus/acpi/devices/PNP0103:00/status 15
/sys/bus/acpi/devices/PNP0C02:03/status 3
/sys/bus/acpi/devices/PNP0C02:04/status 3
/sys/bus/acpi/devices/PNP0C09:00/status 15
/sys/bus/acpi/devices/PNP0C0A:00/status 31
/sys/bus/acpi/devices/PNP0C0F:00/status 9
/sys/bus/acpi/devices/PNP0C0F:01/status 9
/sys/bus/acpi/devices/PNP0C0F:02/status 9
/sys/bus/acpi/devices/PNP0C0F:03/status 9
/sys/bus/acpi/devices/PNP0C0F:04/status 9
/sys/bus/acpi/devices/PNP0C0F:05/status 9
/sys/bus/acpi/devices/PNP0C0F:06/status 9
/sys/bus/acpi/devices/PNP0C0F:07/status 9
/sys/bus/acpi/devices/device:4e/status 15
/sys/bus/acpi/devices/device:4f/status 15
/sys/bus/acpi/devices/device:53/status 15
/sys/bus/acpi/devices/device:66/status 11
> !!Kernel Information
!!------------------
> Kernel release: 4.15.0-20-generic
Operating System: GNU/Linux
Architecture: x86_64
Processor: x86_64
SMP Enabled: Yes
> !!ALSA Version
!!------------
> Driver version:
Library version: 1.1.3
Utilities version: 1.1.3
> !!Loaded ALSA modules
!!-------------------
> !!Sound Servers on this system
!!----------------------------
> Pulseaudio:
Installed - Yes (/usr/bin/pulseaudio)
Running - Yes
> !!Soundcards recognised by ALSA
!!-----------------------------
> !!PCI Soundcards installed in the system
!!--------------------------------------
> !!Advanced information - PCI Vendor/Device/Subsystem ID's
!!-------------------------------------------------------
> !!Modprobe options (Sound related)
!!--------------------------------
> snd_pcsp: index=-2
> snd_usb_audio: index=-2
> snd_atiixp_modem: index=-2
> snd_intel8x0m: index=-2
> snd_via82xx_modem: index=-2
> snd_atiixp_modem: index=-2
> snd_intel8x0m: index=-2
> snd_via82xx_modem: index=-2
> snd_usb_audio: index=-2
> snd_usb_caiaq: index=-2
> snd_usb_ua101: index=-2
> snd_usb_us122l: index=-2
> snd_usb_usx2y: index=-2
> snd_cmipci: mpu_port=0x330 fm_port=0x388
> snd_pcsp: index=-2
> snd_usb_audio: index=-2
> snd_hda_intel: jackpoll_ms=500
> !!Loaded sound module options
!!---------------------------
> !!ALSA Device nodes
!!-----------------
> crw-rw----+ 1 root audio 116, 1 May 5 15:58 /dev/snd/seq
> crw-rw----+ 1 root audio 116, 33 May 5 15:58 /dev/snd/timer
> !!Aplay/Arecord output
!!--------------------
> APLAY
> aplay: device_list:270: no soundcards found...
> ARECORD
> arecord: device_list:270: no soundcards found...
> !!Amixer output
!!-------------
> !!Alsactl output
!!--------------
> --startcollapse--
> --endcollapse--
> !!All Loaded Modules
!!------------------
> Module
ccm
vmw_vsock_vmci_transport
vsock
vmw_vmci
cmac
bnep
nls_iso8859_1
rtsx_usb_ms
memstick
uvcvideo
videobuf2_vmalloc
videobuf2_memops
videobuf2_v4l2
videobuf2_core
videodev
media
btusb
btrtl
btbcm
btintel
bluetooth
ecdh_generic
arc4
iwlmvm
mac80211
hid_multitouch
dell_laptop
dell_smbios_smm
dcdbas
dell_smm_hwmon
intel_rapl
x86_pkg_temp_thermal
intel_powerclamp
coretemp
kvm_intel
kvm
irqbypass
crct10dif_pclmul
crc32_pclmul
ghash_clmulni_intel
pcbc
aesni_intel
aes_x86_64
crypto_simd
glue_helper
cryptd
intel_cstate
iwlwifi
intel_rapl_perf
cfg80211
joydev
dell_wmi
input_leds
dell_smbios_wmi
dell_smbios
serio_raw
sparse_keymap
dell_wmi_descriptor
wmi_bmof
acpi_pad
idma64
virt_dma
shpchp
mei_me
intel_pch_thermal
mei
intel_lpss_pci
intel_lpss
dell_rbtn
mac_hid
sch_fq_codel
parport_pc
ppdev
lp
parport
ip_tables
x_tables
autofs4
rtsx_usb_sdmmc
rtsx_usb
i915
i2c_algo_bit
drm_kms_helper
syscopyarea
sysfillrect
sysimgblt
psmouse
fb_sys_fops
r8169
ahci
drm
mii
libahci
i2c_hid
wmi
hid
video
pinctrl_sunrisepoint
> !!ALSA/HDA dmesg
!!--------------
我以前已多次处理过声音问题，但至少每次通过lspci命令检测到卡时，我都不知道这是否是硬件问题。
更新：
我恢复了默认的 BIOS 设置，现在声卡已经可见。现在的问题是 pavucontrol 中缺少“模拟立体声双工”和“模拟立体声输入/输出”选项。我重新安装了 pulseaudio 和 alsa，但没有用。
答案1
我在 Ubuntu 18.04 上使用 USB 卡（华硕 Xonar U7）时也遇到了类似的问题
我按照这个答案中的说明解决了这个问题https://askubuntu.com/a/1104763/354702作者 João Pimentel Ferreira
1)删除ALSA包。
sudo apt-get --purge remove linux-sound-base alsa-base alsa-utils
2）重新安装相同的软件包。
sudo apt-get install linux-sound-base alsa-base alsa-utils
3）安装更多音频插件包
sudo apt-get install dkms build-essential linux-headers-`uname -r`
alsa-base alsa-firmware-loaders alsa-oss alsa-source alsa-tools
alsa-tools-gui alsa-utils alsamixergui
4）务必将用户添加到音频组
sudo usermod -a -G audio username
5）重启
sudo reboot
答案2
您的音频设备是否被其他进程阻塞了？fuser应该只列出pulseaudio命令：
~$ sudo fuser -v /dev/snd/*
USER PID ACCESS COMMAND
/dev/snd/controlC0: justme 2067 F.... pulseaudio
/dev/snd/controlC1: justme 2067 F.... pulseaudio
/dev/snd/pcmC1D3p: justme 2067 F...m pulseaudio
如果您看到除指定命令以外的任何其他内容pulseaudio，请尝试删除并重新启动 pulseaudio pulseaudio -k（以用户身份，而不是 root 身份）。之后pavucontrol应该会再次列出您的设备...