Two things happen when you hum. You exhale slowly, which is the part of breathing that slows the heart. Evidence: solid And humming raises nitric oxide in the nose about fifteen-fold, which is real and measured but mostly matters for your sinuses. Evidence: decent
The calming effect people report is probably the long exhale plus the vibration giving you something to feel instead of the worry. The only trials are small yoga-breathing studies measuring heart rhythm, not nerves before a hard call. Costs nothing, and you can do it in a car. Evidence: worth trying
Same theme: In the moment
In the moment
Cold water on the face
Cold tap, face in your hands, hold your breath, fifteen to thirty seconds. Repeat twice.
1 minEvidence: decent
In the moment
Hear it today, answer tomorrow
When criticism at work lands hard, say "Let me think about that. I'll come back to you tomorrow." Then go back tomorrow.
no timeEvidence: worth trying
In the moment
The double breath
In through the nose, a second short breath on top, then a long slow exhale through the mouth. Three rounds.
1 minEvidence: worth trying