Some cars (several models of Volvo come to mind, for instance) switch the headlights off while cranking, to get as much current through the starter motor as possible.
Certainly, a good voltage meter never goes astray. You can measure your voltage when you park the car at night, and then do it again in the morning. If it loses more than 0.25 of a volt overnight, I’d seriously consider looking for a short-circuit battery drain somewhere.
Also, if you put your battery on a charger, you can take before and after voltage measurements. A good way to see how “tired” your battery is.
Not knowing what the poster might mean by “humming” I wonder if the starter solenoid has failed and the starter motor is running, without means of being engaged to the flywheel.