Digital audio properties

Sounds :

-https://www.freesound.org/people/beskhu/sounds/149731/

-http://soundbible.com/1937-Tornado-Siren-II.html -From my point of view, only the tornado siren II from Soundbible sounds the most realistic to me , PingPong from FreeSound its also realistic but not as Tornado Siren II.

But anyways, no sound from Freesound or Soundbible sounds natural to me.

-Photos:

Tornado Siren II

PingPong