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I am on a Dell 15R N5110 laptop with only Ubuntu 12.04.3 LTS installed. The laptop has and IDT High Definition chip 92HD87B1/3. It appears correctly recognised as the codec under HDA Intel PCH.

Basic Setup    *Check EDIT

I have an awful high-frequency interference noise in both my headphones and speakers, but at least when on speakers it's not loud enough to bother me. Using the headphones is almost impossible, though.

I have read around and have tried installing the daily build of the DKMS drivers for Intel HDA - not successful.

I tried modifying /etc/modprobe.d/alsa-base.conf by adding the line options snd-hda-intel model=generic - not successful.

I tried modifying /etc/pulse/default.pa with load-module module-udev-detect tsched=0 instead of load-module module-udev-detect- not successful.

Also, I tried isolating the device that is giving off the noise through alsamixer. The result is the following:

  • I cannot mute nor disable Mic Out/Mic In/Internal Mic/Line In/Digital In (setting the volume to 0 has no effect)
  • I can mute Master/Speakers/Headphones/Beep (muting, even Master, has no effect)
  • I can disable Capture (helped a bit)

Thus, I was able to reduce the noise significantly by disabling Capture. I also tried disabling left or right channel only, but the noise remains strong until I disable both.

My problem is that when I disable Capture, my Internal Mic is muted, which defeats the purpose of having it. After all, I want to be able to Skype/Hangout with people using my headphones and my Internal Mic like any other normal person. When I had Windows installed previously, there was no such problem, meaning it's not a hardware issue. (I don't want to go back to Windows, so that solution is out of the question.)

The way I understand the situation is that Capture is the "service" that gets the input sounds in a mix so they can be recorded/outputted, but it should not be able to send them directly to the output. So the problem is somewhere after that. But I have no idea what is controlling it and how to influence it.

TL;DR: Disabling Capture in alsamixer helps, but doesn't solve the problem.

So what do I do?

EDIT:

The daily drivers have changed the audio setup a bit, but the problem still remains the same.

New Setup

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