3. The pronunciation of '-ed'

'-ed' appears at the end of regular verbs in the past tense (e.g. wanted, helped, studied) sometimes in adjectives ending in '-ed' (e.g. tired, embarrassed, relaxed) as well as in some past participle .

However the pronunciation of '-ed' sometimes causes problems because it can be pronounced in three different ways: as / id /, as / t / or as / d /


  • When an infinitive verb finishes with the sound /t/ or /d/ then, we have to add the syllable of the past participle /id/

    • Wanted /id/,  regarded /id/,  calculated /id/, added /id/

  • When the last sound of the word vibrates in vocal cord, we have to pronounce the «ed» like a sound /d/

    • Ruled /d/, died /d/, fined /d/, arranged /d/

  • When the last sound of the word doesn’t vibrate in vocal cord, then it is pronounced /t/

    • Hoped /t/, hacked /t/,

    • focused /t/, wished /t/


Recap

Source: http://www.grammar.cl/english/pronunciation-ed.htm