ASK TOM: A faint cracking sound immediately before blast of thunder?

Dear Tom,
Years ago lightning struck something near our house and I heard a faint cracking sound immediately before the huge blast of thunder. This happened again a few days ago. Is there an explanation?

J. Johanssen, Eau Claire, Wisc.
Dear J.,
Lightning expert Ron Holle of Tucson, Ariz., tells us hearing such a sound requires being within a few hundred yards of the ground strike point. Holle explains that “The clicks may have been static discharge from upward streamers from the house, the ground, or other nearby objects; these are released just when a flash strikes the Earth’s surface. Or, there may have been a buildup of static charge on parts of the house just before the strike. Sometimes on (AM) radios, you can hear this buildup as a whine or series of clicks until the flash strikes the ground.”