Help with listening for RI.

So... long story short I cant hear very well. How can I keep an eye out for RI f I cant hear it? I know what to look for, but hearing the whistling or popping when breathing is the best way to catch it early. Should I get a small stethoscope to help me listen? and maybe check once a month?

For example when my snakes hiss I cant hear it. I can see them hissing, but I am unable to hear the sound.

Not sure how much a stethoscope will help you...might be better if a friend listens for you? You can still watch the mouth for bubbles & excess mucus.

Sometimes feel the congestion in the snake's neck when it breathes. It feels a bit like a water hose with air bubbles being pushed through it.

There will usually be visual signs as well - drooling, bubbles, the snake lying with its head and neck straight up to help keep its airway clear, etc.