How to kill TV like static noise in my Linux microphone?

Question

I was capturing audio using alsa/pulse, or even without any microphone. But always i have this sample static noise.

Similar to those (you can hear the exact noise what i have now):

Sample 1

Sample 2

Sample 3

Sample 4

How do i kill such noise, even without using any microphone?

Follow up: Misterious analogue audio

1) PC1: alsamixer i mute all my mic

2) PC2: i connect my laptop speaker-out to PC1 microphone in

3) PC1: volume 100%

4) PC2: i hear sounds of PC1

That really proves how blindly he is capturing any kind of noises.

Answer 1

Short answer: you cannot.

Long answer:

• the noise originates because you have an onboard soundcard that picks up all noise in your computer. This is a test that proves it on almost all pc's I ever tried: plug in your speakers, make sure no audio is playing, and turn the volume to the max. You here noise. Now move your mouse and you should hear a different noise.. So, you cannot do anything about the source of the noise.
• the noise is almost white noise, which means it contains pretty much all audible frequencies. Hence you cannot apply a digital filter one it, because a filter that removes all frequencies would leave you with silence only. So, you cannot get rid of the noise using audio processing.

The only way to get decent sound in and out of a computer is using an external soundcard (these can be cheap). Or a very pricy internal one.