[Pfiffer]

Anecdata point of one, but I voice the H on hypothesis. Im a native American English speaker, but from the northwest.

[hammock]

"Voiceless" in this context means you dont engage your larnyx/vocal cords (you don't create a pitch), not that you don't sound it out. Compare a whispered "ahhh" - voiceless - vs the "ahh" you say at the doctor - voiced.