I want to add an interesting personal experience. My native language is a Northeastern dialect in China. The dialect doesn't distinguish well the sounds between

I want to add an interesting personal experience. My native language is a Northeastern dialect in China. The dialect doesn't distinguish well the sounds between /z/ and /zh/, between /c/ and /ch/, and between /s/ and /sh/. I went to Beijing for college, started speaking Mandarin, and picked it up quickly. But until now, I still regularly make the mistake between /z/ and /zh/, and the other two pair. I am able to easily tell the differences between the sounds themselves. If the sounds are included in a sentence, however, I simply can't tell which is which. Here is the interesting part. I have no difficulty in distinguishing these sounds in English. I can clearly hear the differences between words like 'sip' or 'ship', no matter if they are spoken as single words or are part of a sentence. My ears will immediately catch the difference. But if it is Mandarin, i will get lost between words like 'ziji' and 'zhiji'.