When learning a second language, it is important to be open to different sounds that are not present in your native language. There are some fairly obvious ones such as tones in Chinese and clicks in Zulu and Xhosa but most languages will contain some sounds that you are not familiar with. I remember spending quite some time in French class at school trying to replicate the nasal n, the r and the eu sounds.
In Dutch there are also a few such sounds, the most famous will be the g sound in gezellig, for example. This sound actually differs, becomes softer, from north to south, but is usually taught as similar to ch in Scots, e.g. loch and in German, e.g. Bach. My favourite example of this sound is actually the famous painter’s name, van Gogh, which has this sound at the beginning and end of Gogh and no, it is not pronounced Go! As a Scot, I personally had no problem with this sound, though it is challenging for many other native English speakers.
My problem was differentiating between the sounds spelled ou and ui, for example, hout and huid. To me, these two words, sounded exactly the same. I could not differentiate them at all.
To explain, you need to know that in Dutch, voiced consonants are pronounced unvoiced at the end of words. So d is pronounced t and b is pronounced p. (The mnemonic, ‘t kofschip, is a reminder of the unvoiced consonants in Dutch). If you don’t know what voiced and unvoiced means, hold your voicebox between thumb and forefinger and say buh and puh, and you will feel a vibration for the b which means it is voiced. e
I have explained the confusion between t and d in hout and huid, but what about the vowels. This comes down to my Scots upbringing. To me, the ou sound (like ow in English (think of How now brown cow)) ui is a sound that is rendered by saying e while shaping your lips for u . At first, I heard them as the same sound. It was as if my ear transformed the sound into something else. Once the difference was pointed out to me, I was able to distinguish between them. I found a blog post that described the same problem with ou and ui : https://blogs.transparent.com/dutch/the-ui-conundrum/
So, my native Scottish accent helped in one area and was a hindrance in another.
Recently I saw this transformation process in reverse. I mentioned to a Dutch person that I had seen some cygnets (young swans) and she was rather puzzled. I wrote down the word cygnets and she wrote what she had ‘heard’: sickness. She transformed the hard g, which is rarely used in Dutch (I can only think of the borrowed word garage) into the softer form of ck. She also transformed the ts into ss in order to make it sound like a word she recognised.
From this, I can offer some advice when learning to speak a new language. If your teacher is telling you that you are pronouncing something wrongly, but you can’t hear the difference, try looking carefully at the shape of their mouth when they make the sound. This may help you replicate the sound correctly.