internal microphone doesn't work

Two systems are affected: Dell Inspiron 5323(201203-10656,201203-10655)

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image-3.2.0-24-generic 3.2.0-24.38
ProcVersionSignature: Ubuntu 3.2.0-24.38-generic 3.2.16
Uname: Linux 3.2.0-24-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
ApportVersion: 2.0.1-0ubuntu5
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: PCH [HDA Intel PCH], device 0: HDA Generic [HDA Generic]
   Subdevices: 0/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: ubuntu 1481 F.... pulseaudio
 /dev/snd/pcmC0D0c: ubuntu 1481 F...m pulseaudio
CRDA:
 country TW:
  (2402 - 2472 @ 40), (3, 27)
  (5270 - 5330 @ 40), (3, 17), DFS
  (5735 - 5815 @ 40), (3, 30)
Card0.Amixer.info:
 Card hw:0 'PCH'/'HDA Intel PCH at 0xd0610000 irq 45'
   Mixer name : 'Intel PantherPoint HDMI'
   Components : 'HDA:10134213,1028055b,00100100 HDA:80862806,80860101,00100000'
   Controls : 12
   Simple ctrls : 5
Date: Mon Jun 4 14:55:50 2012
HibernationDevice: RESUME=UUID=5fb83afa-3c25-4487-9cf6-2880b588128f
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
MachineType: Dell Inc. Inspiron 5323
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-24-generic root=UUID=9588a25a-0c31-4b4e-9d92-7543d0ee68d8 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-3.2.0-24-generic N/A
 linux-backports-modules-3.2.0-24-generic N/A
 linux-firmware 1.79
SourcePackage: linux
StagingDrivers: rts5139 mei
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 02/21/2012
dmi.bios.vendor: Dell Inc.
dmi.bios.version: X22
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: A3E3C3
dmi.board.vendor: Dell Inc.
dmi.board.version: FAB1
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.chassis.version: 0.1
dmi.modalias: dmi:bvnDellInc.:bvrX22:bd02/21/2012:svnDellInc.:pnInspiron5323:pvr:rvnDellInc.:rnA3E3C3:rvrFAB1:cvnDellInc.:ct8:cvr0.1:
dmi.product.name: Inspiron 5323
dmi.sys.vendor: Dell Inc.