What you describe is not selective hearing or controlling. After about 70, people seem like they are hard of hearing. Reason being is your message takes longer for brain to register, so in that time, recipient will often use the word "pardon", to gain time for message to reach brain. After awhile it becomes a habit, sufferer may or may not be aware of this.

Hello there,

I am uncertain if my message will reach you but thought I would respond anyway in the event that my response might help some other forum user to guarner knowledge from my posting.
I went deaf inexplicably overnite following a long period of malnutrition and a sudden adrenaline surge which we feel has overloaded my auditory nerves and contributed to if not caused the deafness. I had a very serious flu some months before hand and didn't take anything for the sickness. At any rate over the years my mother has repeatedly said "your hearing is getting much better!" while my audiological evaluations have always come back the same. When I am in the process if getting to know someone and they find out that I am legally deaf, they fail to understand how deaf people function, which contributes to a misunderstanding of how deaf we are and how we cope in day to day life. Let me give you some examples.
If at the beginning of a day I am out and about transacting business and I come upon someone in the street or a business and they speak first I am most assured that they are greeting me! It makes sense even if I can't hear what they have said which is the case a great deal of the time. I try to lead the conversations so that I get what I need from the people around me. If I happen to be with someone whose timber of voice I can understand then it is easier to allow them to lead the conversation as I am confident that I will answer accordingly and not look the fool! If in the process of conversation even with someone whose voice I can understand and they rapidly shift topics without a hint in the conversation I will be caught dead on and will have to share with them I don't know what they have said "I can't hear you pardon me? Please repeat/rephrase what you have said so I can pick up the conversation again". This knocks them for a loop as they believe my hearing to be better than what it actually is. A lot of our hearing is predicated upon "knowing what we are talking about currently" and these clues come from all around us whether the hearing people recognize them or not!
I thought knowing this might make a difference in how you interact with your parent.
I am currently trying a healing modality from Dr. Christopher I hope meets with some success. Namely the use of Ear and Nerve coupled with Dr. Christopher's Garlic oil 4-6 drops nightly for 6 nites followed by ACV + distilled H2O on the 7th resting that night and resuming again the following eve. Here's hoping!