My son is 7 months old and he has the highest pitched cry I’ve ever heard 
Nothing wrong with his hearing - he was a really choked up c section baby who had the most in-depth hearing test because the mucus didn’t clear and his was perfect.
He’s a happy smiley boy, laughs loads at me, his brother and DH. Rolls about and is trying to crawl but oh my goodness his high pitched cry could break glass!!