All the obstruent consonants are subject to voicing (before voiced obstruents except ) or devoicing (before voiceless consonants and at the end of words); spelling in these cases is morphophonemic (i.e. the morpheme has the same spelling as before a vowel). An exception is the cluster , in which the is voiced to only in Moravian dialects, while in Bohemia the is devoiced to instead (e.g. "shodit" , in Moravia ). Devoicing changes its articulation place: it becomes . After unvoiced consonants is devoiced: for instance, in 'three', which is pronounced . Written voiced or voiceless counterparts are kept according to the etymology of the word, e.g. "odpadnout" (to fall away) - "od-" is a prefix; written is devoiced here because of the following voiceless .