I had two thoughts spring to mind.

What is our outlet for being an adult person without kids? I know I say that like "Everyone MUST have time/energy/money to achieve that" but that's not what I really think. The number of hours I can listen to a four-year-old talk directly corresponds to self-care. It sounds like you are getting none, zero, and that's a big problem. I love the White Album. It's great. But if you played it in my ear all day, every day, with no breaks, and no other music, just a loop of Helter Skelter and Back in the USSR, I'd want to gnaw my arm off. A four-year-old has really only learned maybe three to five conversational pieces and they are going to do them again, and again, and again. They're learning, but it's annoying. But it isn't that your kid is super special in being obnoxious, it is that you're not getting any breaks. None! You are just living in the tape loop of the noises that come out of that kid and that's an objectively terrible thing.

And a big part of what he's practicing is how to talk so that he does get good attention and not bad attention, so it isn't necessarily true that you should just drop everything and give him your full attention. It is important that he learns that this is obnoxious and socially antagonistic behavior. In that gentle, loving, patient, sweet way a parent teaches that lesson, but still...irritating people is part of the lesson on what not to do. Learning what does and doesn't grate on mom is part of the process so you're not a terrible person for having a human reaction to this. I know you're probably swallowing the urge to scream "SHUT UP!" half the day, but that's how it is.

So, I guess that's my advice in a nutshell. Try to get some breaks from the tape loop. Drive to the Hardware Store, put the car in park, listen to two chapters of an audiobook. Try to get a break now and again, it'll make it better. I know that's impossible, but that is all I know to do. But then try to not judge yourself for hating what's objectively a terrible thing and give yourself some kudos for not screaming at this kid to be quiet every day. He is absolutely testing what's pro-social and anti-social in terms of the sounds he makes and your bad reaction is a part of it. You're not a terrible parent for having a human reaction. Finding this annoying isn't failure; it is an honest human reaction. He IS learning so he's going to get some better skills and more self-control and this will improve over time.