Laying out the options
I’m explaining three rules for pronouncing the -ed suffix. If the base word ends in /t/ or /d/, the -ed sound is /ɪd/ or /əd/. If it ends in a voiced sound other than /d/, the sound is /d/. If it ends in a voiceless consonant other than /t/, the sound is /t/.
Reasoned about past tense pronunciation rules for 6 seconds