Every language uses its own set of sounds. And when someone starts learning a new language, it tends to use the sounds of its native language instead of those of the new language, which are generally somewhat different.
For instance, during a French lesson, as a student in France, I could not understand what was wrong with my pronunciation of “Paris” in French. Then Winnie Poon, from Hong Kong, who was sitting next to me, lent over and she said: its not ‛n æ i‛n pæris i‛n fre‛ntʃ  kaa‛ntʃ yuu hii·ə ðə difr‛ns saim‛n And I felt really silly.
Language is more than a means of communication, it also embodies a culture. To successfully learn a language, one has to accept this. It means seeking to pronounce the language accurately, and also surrendering to its logic.