I have difficulty hearing in my left ear. I have difficulty hearing in my left ear.

This sentence is good. Another common way to say this in English is: "I am hard of hearing in my left ear."

In particular, I won't notice if a man with a low tonvoice calls out to me from my left side. In particular, I won't notice if a man with a low voice calls out to me from my left side.

In particular, I won't notice if a man with a low tonvoice calls out to me from my left side. In particular, I won't notice if a man with a low voice calls out to me from my left side.

or, more likely, 'a man with a low voice TALKS to me on my left side'. That is, 'calling' is by definition louder than talking so you might hear him even if he is on your left side.

In addition to mySince I already have difficulty hearing, it's too hard to hear lately because wearing masks makes sounds so muffled I can barely hear at all. Since I already have difficulty hearing, wearing masks makes sounds so muffled I can barely hear at all.

My correction makes the sentence more streamlined and (I think) match closer to the tone/meaning of the Japanese version. Only correcting the grammar would be: "In addition to my difficulty hearing, it's too hard to hear lately because wearing masks makes sounds muffled."

In addition to my difficultybeing hard of hearing, it's tooeven harder to hear latelythese days, because wearing a mask makes sounds muffled. In addition to my being hard of hearing, it's even harder to hear these days, because wearing a mask makes sounds muffled.

You could better distinguish between the ongoing condition of being hard of hearing and the current hearing problem due to wearing a mask. It's difficult because 'hearing' is the main word in both cases.