Voiceless spirant. Make a narrow aperture of your mouth and throat, leave your vocal cords aside, and force air through. Create friction, steam up the mirror. Huh. Hah.
Placed at the beginning of a word this letter sounds like a modern English H: a very light exhalation of the breath. In the middle or at the end it toughens up, sounds stronger, the spirancy has some voice to it, it’s a clearing of the throat not to be found written with an H in modern English, but just ask Bach who would have given this sort of H some voice, especially when sitting by the loch at nicht. In Old English give them all a sound, every H, heed me well there is no silent H here, I am happy to say. But in modern English? H is being dropped all over the place. H is an heir to naught, almost a ghost.
Stand up two parallel lines. Now lean two more between them, let them drop a little.