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Would a hyd accumulator do the same thing?

In essence the acoustic ball was a passive accumulator i.e. no pre-charge or check valves....much like the water hammer device attached to the washing machine hoses in your house.  In the case of the two different aircraft manufactures both hyd systems had accumulators perhaps ten feet of line from the pump close to the reservoirs before it reached the first accumulator.  The Lear did not have the acoustic ball close to the pump and where we had issues....the Citation had the acoustic ball modification installed close to the pump with none of the issues, hydraulically, that the Lear had.  This thing was a stainless steel sphere plumbed into the pressure line.....the shape may have been the magic sauce absorbing the impulses.

Oh I bet that is a pricey little device, has to be pressure rated for the hydraulic system. Like you said, maybe a piece of pipe will suffice to act as the same thing, much less expensive. As you said, maybe there is something to the sphere shape. Looks like as Richard mentioned there are hydraulic accumulators you can buy, they look like they are similar to the ones that Rolls Royce used on their cars, they are charged on one side with nitrogen, with a diaphragm inside.