I definitely relate to this!

Just happened a month or so ago when I saw my old friend for the first time in years. I had a high pitched voice - I definitely knew I was doing it and I tried to lower the town of my voice to a more manly level - but I just couldn't stop talking like a younger child. I even had discomfort in my throat / vocal cords by trying to shift... It was horrible!

I also notice this happens with people randomly. It's both with males and females, any age really.

My theory is that I'm struggling to fight back emotions - and my subconscious wants to desperately leap forward and hug the other person tight. I feel this come in waves - it can come and go while in the presence of someone who I feel safe around.