How to Pronounce -ed

In 3 ways - / Id/ or / t/ or / d/

If the base verb ends in one of these sounds:		example base verb*:	example with -ed:	pronounce the -ed:	extra syllable?
unvoiced	/t/	want	wanted	/ Id/	yes
voiced	/d/	end	ended
unvoiced	/p/	hope	hoped	/ t/	no
	/f/	laugh	laughed
	/s/	fax	faxed
	/S/	wash	washed
	/tS/	watch	watched
	/k/	like	liked
voiced	all other sounds, for example...	play	played	/ d/
		allow	allowed
		beg	begged

* note that it is the sound that is important, not the letter or spelling. For example, "fax" ends in the letter "x" but the sound /s/; "like" ends in the letter "e" but the sound /k/.

Exceptions

The following -ed words used as adjectives are pronounced with /Id/:

aged blessed crooked

dogged learned naked

ragged wicked wretched

So we say:

• an aged man /Id/
• a blessed nuisance /Id/
• a dogged persistence /Id/
• a learned professor - the professor, who was truly learned /Id/
• a wretched beggar - the beggar was wretched /Id/

But when used as real verbs (past simple and past participle), the normal rules apply and we say:

• he aged quickly /d/
• he blessed me /t/
• they dogged him /d/
• he has learned well /d/ or /t/

from : https://www.englishclub.com/pronunciation/-ed.htm