[HP Z820] external microphone does not work, only records noises

[kaxing]

Records with a lot noises, barely can heard the sound.

Step to reproduce:

1. plug your microphone to the front/rear micrphone jack
2. turn up the microphone volume in the system > sound settings
3. open a terminal then type command: arecord test.wav, ctrl-c to inturrupt when you finish

Expected result:

when playing the recordings it should plays recognizable sound.

Actual results:

A lot noise in the recordings.

Additional information:
In the attached recording file, you should hear, "Testing, One, Two, Three, Four, Five ".

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: alsa-base 1.0.25+dfsg-0ubuntu4
ProcVersionSignature: Ubuntu 3.13.0-49.81-generic 3.13.11-ckt17
Uname: Linux 3.13.0-49-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.8
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: ubuntu 1696 F.... pulseaudio
 /dev/snd/controlC0: ubuntu 1696 F.... pulseaudio
CurrentDesktop: Unity
Date: Wed Apr 8 01:32:46 2015
InstallationDate: Installed on 2015-04-02 (5 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
PackageArchitecture: all
SourcePackage: alsa-driver
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/25/2014
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: J63 v03.69
dmi.board.asset.tag: 2UA4242K12
dmi.board.name: 158B
dmi.board.vendor: Hewlett-Packard
dmi.board.version: 1.01
dmi.chassis.asset.tag: 2UA4242K12
dmi.chassis.type: 6
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvrJ63v03.69:bd03/25/2014:svnHewlett-Packard:pnHPZ820Workstation:pvr:rvnHewlett-Packard:rn158B:rvr1.01:cvnHewlett-Packard:ct6:cvr:
dmi.product.name: HP Z820 Workstation
dmi.sys.vendor: Hewlett-Packard

[Keng-Yu Lin (lexical)]

@yung, can you open `alsamixer` then try to lower the gain or volume. see if with lower volume or gain, clear sound can be recorded.

[Raymond (superquad-vortex2)]

you were recording at 64.50dB

Simple mixer control 'Front Mic Boost',0
  Capabilities: volume
  Playback channels: Front Left - Front Right
  Capture channels: Front Left - Front Right
  Limits: 0 - 3
  Front Left: 3 [100%] [30.00dB]
  Front Right: 3 [100%] [30.00dB]

Simple mixer control 'Capture',0
  Capabilities: cvolume cswitch
  Capture channels: Front Left - Front Right
  Limits: Capture 0 - 31
  Front Left: Capture 31 [100%] [34.50dB] [on]
  Front Right: Capture 31 [100%] [34.50dB] [on]