A voice one simulates to disguise inside feelings/emotions or sexual excitement. It's usually necessary when someone, being sure you’re NOT busy, knocks on your door or phones you at a very inappropriate moment.
Last night my mum knocked on my bedroom’s door to say that dinner was ready just when I was blowing the load into my gal! I just took a deep breath and said: "aaaaalright!". Dude, I just hope she could NOT read my poker voice...