The –ed suffix is used to form past tenses.
The suffix of past simple -ed is pronounced as /t/ when the infinitive form ends in a voiceless consonant sound
- Voiceless consonant sounds are: /p/, /k/, /f/, /s/, /ʃ/, /tʃ/, /ð/
The suffix -ed is pronounced as /d/ when the infinitive form ends in a voiced consonant sound
- Voiced consonant sounds are: /b/, /g/, /l/, /m/, /n/, /z/, /j/, /v/, /ng/, /θ/
The suffix -ed is pronounced as /id/ when the infinitive form ends in t or d.
External link to Suffix: -ed exercises (1235).