In general words that end with “-ed” sound like “duh” at the end. And in general, words that end with “-ed” have the same number of syllables as the non “-ed” version of the same word.
There are TWO EXCEPTIONS, (1) and (2).
(1) If the base word ends with a D sound or at T sound then the “-ed” version will have ONE ADDITIONAL SYLLABLE.
(2) If the base word ends with a K, P, S, CH, SH, F sound the “-ed” version of the wordd will sound as if it has a T at the end! King Pepe said, "Children shouldn't fly."
f laugh, laughed (lafT) s...relax, relaxed (relaksT) k...pick, picked (pikT) ch...touch, touched (tuchT) sh...push, pushed (pushT)