It's probably a learning process for sounds that are typical in a language. Later in life we can also distinguish different languages even though we don't speak them. Many non-English-speakers will still identify a song like https://en.wikipedia.org/wiki/Prisencolinensinainciusol as being English, even though it only uses sounds that are typical for English.

I started learning Arabic at about 45, and many sounds I've learned to make with my mouth, but I can not distinguish with my ears when other people speak. For instance ك/ق or س/ص or د/ض.

It's as if my brain is binning these sounds together and I can not retrain the binning.

Can you hear the difference when you ask someone to really exaggerate their articulation and enunciation? Because with most languages I speak I tend to have difficulty understanding people when they don't talk like a radio weather forecaster.

Other than asking people to talk slower, I haven't tried asking people to change their speech. Maybe I should.

Well, two of them you mentioned, ض/ص you can imagine the tongue making a bowl shape when you say them.

Saying/hearing is not the same. Parent struggles to hear the differences and says they can pronounce them.

Polish has a retroflex and palatalized “sh” pair of sounds (Sz vs ś) that I can pronounce perfectly but not clearly distinguish as a listener.

I learned Polish when I was 5, moved back to the states when I was 11, barely used it for 7 years, and relearned it when I was 18. I don’t know if (at 5) I ever distinguished between the two. But I certainly struggle now.

Same for me with Dzongkha: cha (ཅ) / chha (ཆ) and tsa (ཙ) / thsa (ཚ). I can aspirate the second of these fine, so that's not the problem. Hearing the difference is. This also makes it harder to remember the spelling as I mix them up all the time.

To be fair, I've only been learning for a short while (8 months or so) and haven't had much opportunity to listen to a lot of different speakers so perhaps this may get better.

If it’s anything like the aspirated consonants in Hindi, usually the aspirated one of the pair ends up being sounded out slightly longer because of the expelling of breath. That’s how I learned to recognize it. Aspirating was actually much harder for me at first than hearing it.

Thank you. Yes, I am able to articulate the sounds more or less.

That said, any other tips on pronunciation are greatly appreciated! I did not realise that the tongue makes the same shape with both letters - I was not making a proper bowl with ض.