An unvoiced phonetic is not actually a proper sound, but air being pushed air through a shape made by the back of the throat, mouth, or tongue (against the roof of mouth, teeth, or nothing at all) A voiced phoentic is actually a sound, created by the vibration of the vocal chords, uvula, tongue, or something in the mouth that makes the air in the mouth cavity oscilate.
So I get that much.
I cant find any usage for the spanish ñ sound. Is it even needed, cant just a n+y sound be used? The same with the ll sound, can't just l+y be used? I get dh and nj now, thanks.
Even in pronouncing "oh-ee" fast, the oh and ee parts are distinct, unless u slur them together, which would be creating a new phonetic would it not? I still have a problem with two. Try saying "Tew", "too" and then two like u normally would, perhaps its my nothren candian french/native accent influencing something, but i hear a 'u' like sound.
I find a big difference in CH comparred to TSH, but i seem the similarity of J to DZH, but i think J is unique again.