I have the same issue on an Aspire. Ubuntu 12.04LTS 64bit

realtek audio sound chip onboard

If I plug in a headset, audio does not switch from internal speaker to headset, instead plays out of both at the same time.

I have looked at the alsamixer setting, all on.

I installed gnome-alsamixer, and I noticed headphone was ticked, if I untick the main audio mutes, and the headphone no longer works. Headset only works with internal speaker.

Audio works fine on my other desktop and laptop running this release

00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03)

salvatore@salvatore-Aspire-7730:~$ cat /proc/asound/version
Advanced Linux Sound Architecture Driver Version 1.0.24.


salvatore@salvatore-Aspire-7730:~$ head -n 1 /proc/asound/card*/codec#*
==> /proc/asound/card0/codec#0 <==
Codec: Realtek ALC888

==> /proc/asound/card0/codec#1 <==
Codec: LSI ID 1040

==> /proc/asound/card0/codec#2 <==
Codec: Intel Cantiga HDMI


salvatore@salvatore-Aspire-7730:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC888 Analog [ALC888 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 1: ALC888 Digital [ALC888 Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0


salvatore@salvatore-Aspire-7730:~$ uname -a
Linux salvatore-Aspire-7730 3.2.0-23-generic #36-Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
salvatore@salvatore-Aspire-7730:~$ 

The alsa-base.conf does not exist

Tried this:

sudo apt-get remove --purge alsa-base

sudo apt-get remove --purge pulseaudio

sudo apt-get install alsa-base

sudo apt-get install pulseaudio

sudo alsa force-reload

Then:

sudo apt-get purge pulseaudio gstreamer0.10-pulseaudio

sudo apt-get install pulseaudio gstreamer0.10-pulseaudio indicator-sound

Tred this.

sudo gedit

Then open terminal:

sudo /etc/modprobe.d/alsa-base.conf

At the end of the file add a new line:

options snd-hda-intel model=generic

Save and then reboot

But alsa-base.conf does not exist