Briefly, until I get round to doing this properly:
"fronting" means the move from dental fricative (■,) to labiodental fricative (f,v) -
think /■iNk/ -> fink (fiNk/
mother /m7@/ -> muvver /m/v@/
BUT remember that initial does not front in structural words, the this that,
instead it lenites to zero, n, l, d-flap or the like. Might call this TH Weakening
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