This is a nice example from Australian band Darts. They trade vocal duties within the band between male and female. This song features the latter:
This is a great song from Phoenix, AZ band the Numb Bats, with their one word lyric "Runnin":
This band, Feature, has an excellent song from their album "Culture Of The Copy":
The guitar sounds for this San Francisco band, Grass Widow, aren't necessarily harsh, but the vocal harmonies are so sweet, that the contrast is still there:
Indie queen Mary Timony has a regular rock voice, but is so adorable that the contrast comes from the harsh guitar sounds coming from that timeless cuteness:
One of my favorite bands at the moment is Cardiff group, Joanna Gruesome:
The pioneer band for mixing Ramones-style chords and sweet voices is Shonen Knife. They've been doing it for almost 35 years (at least lead singer Naoko Yamano):
I'm building a playlist at SoundCloud with Harsh Guitars and soft voices:
https://soundcloud.com/markhdz/sets/harsh-guitars-soft-voice