Ive heard the distinct sound of a longtime coworker clearing his throat, in his old work space. Hes been gone since 2006.
We have recorded orbs in that area, no EVPs, thermal, SLS, or EMF fluctuations. So-far...
As an aside, he is interred in a known haunted mausoleum.
My dad's story was similar. When at the recently-deceased grandparent's house, picking up his coin collection for mom, he said he heard the old man grumbling, as if right behind him.