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Hi there,
I´ve got a question concerning some strange sound produced by Ubuntu.
I recently installed Ubuntu 16.04 LTS 64bit on my laptop. Now I´ve got dual-boot: Windows 7 and Ubuntu.
Installation went just fine and I´m overall really satisfied with it. There´s one thing though I cannot explain.
Every time when performing a reboot in Ubuntu (i.e. from the running system) there is a quite noticeable
cracking sound coming from the left in-built speaker.
To be more precise: Ubuntu has already shut down to the point where the screen has become black. That´s just the point when that peculiar cracking sound can be heard. Just one time, really short, almost metallic.
Yet the reboot is in no way affected by that.
Three more things:
1.) When shutting down Ubuntu completely and then starting from scratch (cold start) that noise is not to be heard.
Only when rebooting.
2.) When performing a reboot from a running Windows 7-system on the same laptop (dual-boot) no cracking sound can
be heard. So it´s definitely a Ubuntu-thing.
3.) For further testing I installed Ubuntu on a USB-stick as well (complete install, not just a live-system).
The same sound could be heard under the same circumstances.
So another hint towards Ubuntu.
I seriously hope that cracking noise doesn´t do any harm to any of my laptop´s components.
But I´d really like to get to the bottom of things. Has anyone any idea what this could be about?
Thanks in advance.
Rosika 
P.S.: System:
- Laptop Medion Akoya E6222
- Audio: Conexant SmartAudio HD (says Windows)
- Gerät: HDA Intel PCH
Chip: Conexant CX20585 (says Ubuntu)
Hi Rosika
Haven't heard from you in awhile. Since you have moved on to Ubuntu 16.04 I would bet you are having issues with the pulseaudio drivers. I had a similar experience with Mint 17.0 but not with 17.3. If you haven't already done so then you need to open a terminal and run the "sudo lspci -v" command, you will have to scroll down to the Multimedia Audio Controller. Make note of the driver and maybe do a search on the Ubuntu Forum. You might also consider rolling back to 14.04, if it did not have this issue.
Hi Daniel.
so nice to hear from you again. I hope you are well and everything is alright.
Since our last "virtual encounter" things have proceeded qite a bit.
On my PC (WIN8.1) I am running Ubuntu and LinuxMint as VMs. And as long as WIN8.1 is supported I think I´m going to use that as a productive system.
As far as my laptop is concerned Windows7 will get support until January 2020 as far as I know.
The possibility of dual-booting is really fascinating for me. So thought I´d give it a try and after shrinking my C:\-partition I installed Ubuntu as a second OS.
So that´s the state of things.
And I must say that Ubuntu works very nicely, and no problems with graphics either.
That was the original headache given to me by Microsoft (WIN10).
And apart from the cracking sound I described in my post and from some sort of beeping sounds (for the lack of a better word) when Ubuntu accesses the hard drive (or rather RAM????) everything is as it should be. But perhaps those differences strike as so obvious when one is accustomed to using Windows for such a long time.
As for your suggestion:
First of all: thank you very much.
Second: Hopefully I´m going to try that out tomorrow. Today, alas, my internet connection is very poor (to say the least). I´ll be glad if I can post this message.
I´m going to get in touch with you as soon as I can report something new.
Until then Goodbye and thanks again.
Rosiika 
Hi Daniel,
sorry it took so long to respond but my internet-connection is very unreliable at present.
run the "sudo lspci -v" command, you will have to scroll down to the Multimedia Audio Controller. Make note of the driver
What I found out was the following:
Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 05).
Subsystem: Pegatron 6 Series/C200 Series Chipset Family High Definition Audio Controller
[...]
The only thing about drivers was:
Kernel driver in use: snd_hda_intel
Kernel modules: snd_hda_intel
So far so good, but I´m not a lot wiser .....
Greetings
Rosika
OK, that is your Audio Controller which is probably being controlled by Ubuntu's PulseAudio driver. I do believe the conflict lies with Ubuntu's use of both ALSA and PulseAudio, that is why a lot of Ubuntu and Mint users will purge PulseAudio and use ALSA and the alsamixer. How to deal with the issue is a different matter and one you should consider very carefully. I am going to give you a link and let you read and decide for yourself as to how far you wish to proceed(.https://help.ubuntu.com/community/SoundTroubleshootingProcedure) (http://askubuntu.com/questions/426983/how-can-i-tell-if-im-using-alsa-or-pulse-audio-by-default-switching-to-i3-wm) here are two links you might consider reading.
For a more detailed description pf your PC you can run the "sudo lshw" if lshw is installed, if it isn't then you can run the "sudo apt-get install lshw".
Sorry, I didn't separate the two links. You need to open the second link.
Hi Daniel,
thank you so much for digging so deeply into the matter. That´s really kind of you.
The link you´ve given me offers a variety of links like https://help.ubuntu.com/community/SoundTroubleshooting and https://help.ubuntu.com/community/SoundTroubleshootingGuide.
I believe that´s what you had in mind.
Sounds like that makes a lot of interesting reading. I´m curious to find out whether that´s going to help.
How to deal with the issue is a different matter and one you should consider very carefully.
Thanks for that word of warning. The last thing I want to do is wreck my system.
In the long run the fact remains that a reboot is not needed on a daily basis. So the "annoyance" of that cracking sound should be kept within reasonable limits.Nevetheless
I´m going to see what I can find out with the help of your link.
Thanks also for referring to "sudo lshw".
I´ll be in touch as soon as possible.
Many greetings
Rosika 
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