Does this really apply to, say, tonal languages? I'm trying to learn Vietnamese and I feel like there is a sensitivity to the tones that really needs to be the

Does this really apply to, say, tonal languages? I'm trying to learn Vietnamese and I feel like there is a sensitivity to the tones that really needs to be there early on. Another factor, I'm sure, is that my ears just aren't as good as they were when I was young.