What would a 60 watt Reveal light bulb hum in a ceiling fixture but a regular 60 watt soft light bulb does not?

Dimmers can cause ceitain light bulbs to be noisy due to the way the triac based dimmer chops up the ac sine wave. Different bulbs use different filament structure. The chopped up sign wave can set up vibrations in the filament structure. Some filament structures vibrate more or less.