Voiced sounds after voiced and unvoiced after unvoiced

Why do we need a voiced sound after another voiced sound and voiceless after a voiceless sound in English? Explanation: Often in inflected forms, we need to add a voiced sound after the preceding voiced sound (phoneme) and voiceless sound after voiceless sound (phoneme). For example: Pass -> passed (/st/) Since /s/ is a voiceless sound so we add voiceless /t/ after it rather than voiced /d/.

Hug -> hugged (/gd/) /g/ is voiced so we add voiced /d/.

Another example: Bag -> bags (/gz/)

Bat -> bats (/ts/)

Why does that happen? Thank you.

(Sorry if it's already present. I searched a lot but didn't find anything that could answer my question).

The question is not whether, or how, or when, but why adjacent consonants agree in voicing? This is not always the case, even in English. But it is very common, and enshrined in several rules, like noun plural and verb singular suffixes. And the reason it's common is a physical one. Voicing is controlled by the larynx, in the throat. Consonants are formed by the muscles of the mouth. So voicing is independent of consonants, and needs to be timed. Sometimes the timing is off. It turns out that making consonant clusters all voiced or all unvoiced is just the simplest way to talk. So we do. – John Lawler 1 hour ago

Yes this is someone else's answer, but he clearly didn't want credit for it...