What could this strange vibration noise be?

What could this strange vibration noise be?

Here is a sample you can listen online on Whyp.

Other recordings can be find on GitHub.

What I have confirmed are:

1. It is not ambient
2. It often has an area of effect with a radius less than 1 meter
3. It is distinct from some other normal vibration sources
4. The centres of occurrence can be ordinary things, sometimes right at my head
5. There can have multiple occurrences at the same time
6. Since the area of effect is small, the occurrences I noticed were around/at my head
7. It is faint most of the times, tend to be louder at night with the quietness of night considered
8. Sometimes a centre of occurrence seems to be able to move
9. Other properties such as pitch(frequency), volume(strength) and size can also change or vary

It has been a few months since the first time I noticed it around my head when I was sleeping.

What could it be?