Hello. This question I'm going to ask you guy may require a bit of understanding in phonetics. But I'll try to make it as simple as possible, so please at least take a look. All the notations in slashes and brakets are IPA except ch, j, sh, zh, th. In American English, there is no longer a distinction between [yu] and after alveolar consonants like [t, d, n, s, z, ch, j, sh, zh, y]. So most Americans pronounce the vowels of new/nude, tune/two, dew/do the same. But some people from the South still pronounce them differently. If YOU pronounce and hear them differently, then you can help me. For those who make distinction between [yu] and after alveolar consonants, are the way you pronounce the vowels of cute and tune different? My guess is that your lips are already well pursed in expectation of the following when you pronounce the [ky] of cute, but not as much when pronouncing the [ty] of tune, the reason being trying to avoid sounding like choon instead of tune. And as a result, when you pronounce tune slowly and carefully you sound more like [ti] and [un] slurred together, not [tyun]. OK, so that was my guess. If your natural and non-self-conscious pronunciation of those words are in accordance with my guess, please tell me so, if not, please let me know how they are different. Hope it wasn't too hard to understand for non-phoneticians. Much thanks in advance.