Microphone input volume too low in Cheese, Ubuntu 14.04

Question

Microphone volume is too low to be heard in Cheese and Skype but works ok when I record with Audacity and when I do this:

vlc pulse://

I dual-boot Windows 10 and the microphone works ok in Skype on Windows. I have used pavucontrol and gnome-alsamixer to check microphone input volume levels (not enough reputation to post screenshots)

I use a Lenovo G50-80. More info about my system:

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: HDMI [HDA Intel HDMI], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: HDMI [HDA Intel HDMI], device 8: HDMI 2 [HDMI 2]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: PCH [HDA Intel PCH], device 0: CX20751/2 Analog [CX20751/2 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

$ pactl list sinks short
0   alsa_output.pci-0000_00_03.0.hdmi-stereo    module-alsa-card.c  s16le 2ch 44100Hz   SUSPENDED
1   alsa_output.pci-0000_00_1b.0.analog-stereo  module-alsa-card.c  s16le 2ch 48000Hz   SUSPENDED

$ lspci | grep Audio
00:03.0 Audio device: Intel Corporation Broadwell-U Audio Controller (rev 09)
00:1b.0 Audio device: Intel Corporation Wildcat Point-LP High Definition Audio Controller (rev 03)

$ uname -r
3.16.0-46-generic

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.3 LTS
Release:    14.04
Codename:   trusty

Answer 1

You can try the suggestion in the comment at Sound Input Works in Audacity but not in PavuControl:

If your internal mic is either completely silent (no signal), or you can possibly pick a very small sound, with much background noise, even though you have set gain to maximum, there is something you could try.

Install the pavucontrol application, start it and go to the "Input Devices" tab. Unlock the channels (there is a keylock icon), then mute the right channel while keeping the left channel at the volume you want. If the internal mic is now working correctly, you have an inverted internal mic, so that your right channel cancels out the left one.

source: https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1002978