the manner of noise production (loss of plosion or incomplete plosion);
the place of articulation (in trip alveolar /t/ becomes post-alveolar).
Modifications of phonemes in speech
Voice assimilation is observed when one of the two adjacent [ə̍ʤeɪs(ə)nt] (смежный, соседний) consonants becomes voiced under the influence of the neighbouring voiced consonant, or voiceless - under the influence of the voiced consonant. E.g.:
translate [trənz ˈleɪt], I shoud pay [aɪ ʃt ˎpeɪ].