A single sound is made up of many components. You are missing the speed of the water over rocks, rocks, water falling on rocks, & falling into a large body of water. Also generally there is a cave or echoing. All that and much more creates the thunderous water fall sound.

However, I lived on Maui, and we had a fake water fall, that was louder than the ocean, and it was 20 ft wide with a a washboard that the water ran over, creating a waterfall sound. It wasn’t the real sound, but it is the closest I’ve heard that was mechanical.

The wideness and the rocky washboard makes the splashy whoosssh sound.

I’m a musician and into sound physics for uses health and fun.
Peace Ann Moss

I noticed that your “waterfalls” are thin in diameter. What about increasing the surface area of the waterfall? Making the waterfall longer covering more ground than single streams? A diver who belly flops will make a huge sound (and splash) compared to the Gold Medal Olympian who cuts through the surface with no splash.

Every few weeks or so I fill up our 5-gallon water dispenser with five 1-gallon containers. The first 2 gallons always makes much more sound, when there is little water in the 5-gallon dispenser. Maybe it also depends on how much water is in the bucket below?

ALSO, hehe, when we go fill up our 1-gallon containers at one of those “Water Gourmet” treated/filtered water places, multiple 1-gallon containers filling with water is really loud (when the containers are empty/half empty). Louder is when they push a button that shoots pressurized water into the empty containers to rinse them out.

And that, my friend, is the observation of an extreme water drinker. =)

Hope you post progress on your project! Good luck!

that said, that second picture looks incredibly wrong…