My 19 was also pretty annoying at certain RPM's. Chatting with other 19 owners, the problem varied significantly between different outboards. At the time I owned it (several years back), it seemed like Yamahas were the worst by a large margin (mine was an F80) Hondas were better, and the Suzukis the least annoying.
On mine, it wasn't so much the noise, but the resonance and harmonics. Certain RPM's would send a buzz through the air/hull, that was far more annoying than simply excess decibels.
If this description matches what you are encountering, there were three things I did that made a world of difference on my 19. A four blade prop, trim tabs, and a Permatrim.
The four blade prop performs much more smoothly than three, and was likely responsible for the largest reduction in noise. The Permatrim and trim tabs, allow you to fine tune things such that the engine RPM's are in a less annoying range for a given speed. This is particularly helpful at lower speeds, as the 19 typically requires you to throttle up to much higher RPM's/speed to get on plane, than a 22. It's these higher RPM's that were the worst on mine.
Even with the reduction in noise these items provided, I ain't gonna lie...much as I liked the open access to the cockpit and the fishability of the 19, I hated it every time I throttled up. The 22 is soooooo much quieter.