Comment 6 for bug 1737614

Here the same with a Thinkpad T570. The low sound appeared after upgrading from 17.10 to 18.04 or 18.04.1.

$ cat /proc/asound/card*/codec* | grep Codec
Codec: Realtek ALC298
Codec: Intel Kabylake HDMI

$ sudo lspci -vvv | grep -A 40 -i audio
00:1f.3 Audio device: Intel Corporation Sunrise Point-LP HD Audio (rev 21)
 Subsystem: Lenovo Sunrise Point-LP HD Audio
 Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
 Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
 Latency: 64
 Interrupt: pin A routed to IRQ 123
 Region 0: Memory at ec240000 (64-bit, non-prefetchable) [size=16K]
 Region 4: Memory at ec230000 (64-bit, non-prefetchable) [size=64K]
 Capabilities: [50] Power Management version 3
  Flags: PMEClk- DSI- D1- D2- AuxCurrent=55mA PME(D0-,D1-,D2-,D3hot+,D3cold+)
  Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
 Capabilities: [60] MSI: Enable+ Count=1/1 Maskable- 64bit+
  Address: 00000000fee04004 Data: 4021
 Kernel driver in use: snd_hda_intel
 Kernel modules: snd_hda_intel, snd_soc_skl