Therefore, the popular notion that snakes are deaf is not true, although hearing is restricted to a limited range of sound frequencies, from approximately 50 to 1000 Hz (= cycles per second). By comparison, humans can sense airborne vibrations in the range from 20 to 20,000 Hz. By definition, hearing refers to the sensory detection of airborne vibrations by the inner ear, as distinct from very low-frequency vibrational stimuli transmitted by the ground or by solid objects that might be in contact with an animal.
Lillywhite, Harvey B.. How Snakes Work: Structure, Function and Behavior of the World's Snakes (Page 168). Oxford University Press. Kindle Edition.
The voiced speech of a typical adult male will have a fundamental frequency from 85 to 180 Hz, and that of a typical adult female from 165 to 255 Hz.
https://en.wikipedia.org/wiki/Voice_frequency
Besides from my own anecdotal experience with talking to all of my snakes and eliciting responses, I think there is clear scientific evidence that they can hear us talking to them.