I did read the second study report, which states that snakes can only percieve sounds up to 450 Hz, effectively rendering them even deafer than those in the first study you sited.
I still stand by my observations.
Please feel free to believe anything you wish, however, I would urge you to maybe do some experimentation of your own, with your own animals.
It's not that I automatically distrust scientific journal results, it's just that often times they are not searching for the same answers I am. Different expectations often arrive at different results.