If possible take the dogs away from them, kennel them at the vet or a doggie boarding place, leave them at a friends who lives where they are not setting them off close etc.
If they must remain
Bring them in the house
Put them in a room with the radio or tv on fairly loud
If the room has a place they want to hide like a closet or behind a couch let them
Some put rescue remedy (bach flower remedy) in their water or drops on tounge
Spearmint oil on paw pads is also said to calm a dog naturally
Last resort is to get a rx from the vet but still keep them inside and with background noise
do not coddle or tell them its ok, ignore anxious behavior, play if they will play, give a stuffed kong or work on sits, downs etc with treats if the dog will. Some get so wound up they refuse even their favorite food like chicken or beef cubes.
Some dogs can be desinsitized slowly over time but a large % of sound phobia is GENETIC and the dog simply can not help it nor can you train them totally past it. It can also be neurological. Sound sensitive dogs create sound sensitive pups and should never be bred.

