The person I care for is 54 and mumbles constantly. She has the volume up very high and becomes angry when I need her to turn it down and speak up. Her husband has complained about the same problem for decades. Is this part of being on heavy opiates or is it deliberate? She’s very very VERY passive aggressive.
Hearing problem.
Speech problem
Dental problem
Just plain lazy speech
(and no one corrected her when she was young.)
If she mumbles to the point where you can not understand her find a time and place where it is quiet and you have her full attention and she has yours.
Explain so it might be putting the "problem" as your problem. Say something like "I have a problem understanding you and we need to work out a solution so that I can care for you the best that I can."
Offer some solutions.
Speak clearly so that I can understand you better
Speak up so I can understand
Can we turn down the volume on the TV so that I can hear you better?
Can we use a dry erase board and write notes to each other?
Maybe then also say.."If we can not work this out so I can do my best to care for you it might be best if you look for someone that can better fit your needs. I enjoy working with (for) you and I would hate to go but if I can not do my job properly it is not fair for either of us"
Maybe making it "your" problem might not result in a passive aggressive outburst.
I had a dear auntie who always spoke quietly because "that's how a lady is supposed to talk".
Conditions like Parkinson's can also impact the voice.
Before you address this I would get her hearing tested.
My husband worries about being loud so he over compensates and speaks very low, which sounds like mumbling. He doesn't do it on purpose, he can't hear himself so no volume regulation.