So briefly, geese evolved to eat grass. Grass (seed and pasture) crops are a major portion of the ag economy in the Willamette Valley. Scaring or hazing animals off the exact foods they evolved to eat to the point of "exclusion" is effectively impossible, but the animals can and do exact a significant loss to growers - near-term to the coming crop and longer term to potential reduction of productivity on the soils. Winter-long removal of the grass plants' leaves and growth points via goose herbivory, along with compaction of the soil from the many feet on wet soils, can indeed reduce the plants' yields, survival, and even longer-term productivity of the soils (due to compaction).There are journal articles, graduate theses and dissertations, and various articles on the effects, and increasingly in the recent times, about the goose-agriculture-sub/urban issues. The propane cannons likely have some efficacy, some of the time. Animals habituate pretty easily when nothing "bad" happens - I.e., This is food, there's a noise that was scary, but nobody (goose) in our flock got hurt or died, and....back down to the field to eat some more.
Essentially however, farmers have to use what they can - There are not a lot of good options with this crop/wildlife combo. I know there are some private companies offering goose hazing with herding dogs, but I would expect that option is quite costly (every day, all winter into spring, people+dog teams = $$) compared to the cannons. Unless a neighborhood could contribute significantly to carrying that additional cost, I can see where a family farmer wouldn't be particularly eager to switch to that method, but it might be worth (your) research to find out how much it would cost for whichever particular field (size, location) it is you would want to pitch to that farmer. It *might* be possible to talk with a particular farmer to slightly change the direction of the cannons to see if the amount of "boom" being projected to your friends' neighborhood could be reduced.

With other crops in other settings - and against different species of birds (e.g., birds that eat grains such as blackbirds, lots of species that eat fruit, from bush-style crops, etc.), growers have tried distress calls, others employ teams of falconers (flush, not hunt), and in inside (livestock) installations some are experimenting with lasers. But these approaches are not useful for or where - geese are typically causing problems.
 
So briefly, geese evolved to eat grass. That's why they have such stout legs compared to ducks, for example. Grass (seed and pasture) crops are a major portion of the ag economy in the Willamette Valley. Scaring or hazing animals off the exact foods they evolved to eat to the point of "exclusion" is effectively impossible, but the animals can and do exact a significant loss to growers - near-term to the coming crop and longer term to potential reduction of productivity on the soils. Winter-long removal of the grass plants' leaves and growth points via goose herbivory, along with compaction of the soil from the many feet on wet soils, can indeed reduce the plants' yields, survival, and even longer-term productivity of the soils (due to compaction).

Furthermore, in a nutshell, total across-species goose population abundances have recovered to probably 4-5 times (i.e, 400-500% more animals) as large as the popns were at the earliest concerns about grass/grainfield depredation. Some subspecies however, such as the Dusky Canada Goose, are teetering on Threatened/Endangered status and they overwinter in the Willamette Valley every year.

So. What to do? Oregon has a Right to Farm Act that protects tools and practices critical to annual farm activities. As more and more residential neighborhoods have been packed into the urban growth boundaries around cities, more people are being exposed - often for the first time - to the sights, sounds, smells, dust, seasonal moving equip on highways, etc., associated with Ag. Farmers and farm managers are advised by the Oregon Department of Agriculture to be mindful that new/expanding neighborhoods are in among and around areas that were once unbroken areas of ag, and that working productively with concerned neighbors/being a 'good neighbor' is advisable. 
I'll give you contact info for the Dept of Ag below, but really the first and more productive step is for your friends to go talk with their neighboring operator and have a conversation. Demanding that the farmers stop something that is critical to their farming - and is protected by law - won't be a productive strategy, but hopefully some additional "getting to know your neighbors" conversations will produce some willingness to bend on both sides.
As for the impacts on your duck hunting - You can contact your ODFW District Biologist with that concern, and/or the statewide waterfowl/migratory bird manager (B Reishus). They may have suggestions of equally accessible sites that perhaps are less-affected by hazing sounds. 

ODA Complaints, Land use division:
Land use

Land use information

Phone:<personal data hidden>

Email a complaint for issues related to the following:

• Noise
• Smell
• Dust
• Animal trespassing
• Agriculture disputes