Lawn Sprinkler noise - water splashing on window

…but it’s not. This is an intermittent sound that occurs in sessions with some clients. It sounds as if the client has a rotating lawn sprinkler on in the yard that splashes water forcefully on the window pane of the room my client is in. It turns out that the client does NOT have a sprinkler and they do NOT hear the sound. While it was annoying, it did not become an obstacle until it got so loud that I couldn’t here my client.

Anyone know what this is or have any suggestions?