I know the rule of pronouncing s at the end of words(plural nouns and singular verbs) that if s follows a voice sound(d, l, etc.), it will be pronounced as /z/ sound. For example,
"words" is pronounced as word/z/.
However, I believe that I have heard many native speakers pronounce it as /s/ sound.
Did I hear it wrong? or Americans simply pronounce s at the end of "words" as /s/ not /z/