I have actually noticed this with duck calls as well... I have become convinced that temperature plays a role in how the call sounds... The material expanding and contracting due to temperature, or the way the air travels over the call, as well as our own sound chamber (i.e. throat). I am not sure what it is, but I have found with duck calls, that temperature or climate does seem to create some differences in the way some calls sound.
With a latex diaphragm call there are multiple issues that can occur:
- Latex could be sticking together.
- Latex could be stretched.
- Material (such as food) can get stuck in the latex.
- Temperature.
- Confidence at any given moment.
I would not think that temperature would play as large a roll with a diaphragm though, because the call will warm to our own body temperature after being in our mouth for several minutes... I could be wrong, but I do feel there is a sound difference in a call when I take it out of the fridge and start playing it, verses after it has been in my mouth a few minutes and warmed up...
I do believe that confidence is underplayed as well. If I have confidence I can run a call, I can usually make it work... If I don't have confidence with my own calling or ability to run a particular call, it could be the best call in the world, and I still could not run it.