I have noticed that voiceless sound at the end of a word becomes voiced when followed by a word that starts with a vowel. For example: It has affected us (/s/) all => It has affected us (/z/) all. I have also heard it in the following example: Both (/θ/) of you should go => Both (/ð/) of you should go.
Does it happen every time when a voiceless consonant is followed by a word beginning with a vowel? Thanks. :)