PRONUNCIATION of -ed

I hope this explanation helps you clarify this point:

• when the verb ends in a VOICELESS sound (/p/, /k/, /s/...) we pronounce it /t/ (also voiceless)
• when the verb ends in a VOICED sound (/b/, /d/, /g/, /n/, /i/...) we pronounce it /d/ (also voiced)
• when the verb ends in  /t/ or  /d/ we pronounce it  /id/ 

To see which consonants are voiced or voiceless (unvoiced) go here and here. Click and listen. Then watch this video.

Listen to some examples here. You can also have a look at this explanation in our NB2 blog here.
For a good laugh, watch the video in this post (as promised... The Italian who went to Malta). Don't miss it! It's really worth it!