I'm the same with mouth calls raspy yelps but it works! I listen to Dave Owens on Pinhoti and think I suck... lol he is much higher pitched.
IMO, Pitch comes into play when working birds that have been called to a dozen times already in the season.
Think about it... late season, most birds have heard typical 3 Reed mouth calls and pot calls... came to them and busted the hunter to live another day.
Tail end of the season its time to kill a bird with something they haven't heard before. I prefer a very high pitched, almost squeaky 2 Reed batwing.
I also carry a tube call. Didn't pull it out until this past week. When I'm on new ground (about 50% of the time), I'm hauling ass as fast as I can until I strike a bird or find fresh sign. We are down to the last third of the season here in MS, and I'm using the tube to get a reaction gobble just to let me know to stay there for hours playing the subtle stuff to have a chance of fooling one. I've never worked one into the kill with my homemade tube