Two sporty students with two voices

It came out in Frank's male baritone which made the whole scenery rather odd.
"I can relate, Frank! I mean, I am growing wetter 'down there' as well!" Walter said and motioned down on the leotard where a small wet spot was already showing.
"And you know what they say, slippery when wet!" he said.
"Looks like these bodies agree with us. This is hot." Frank said but sounded slightly different in the end. He sounded more like the girl he looked like than like the fat balding man he really was!

"Hehe Frank, the voice... You just sound like a girl now!"
Frank's thoughts were suddenly spinning with many thoughts, but most of all, thoughts about dicks. Big dicks, small dicks, dicks of all ages, teen dicks, old dicks, all the dicks. But there was something about large dicks that just made him get wetter.
"Gosh, Walter... I just thought about the strangest thing! I was horny for dicks! Dicks!" As he spoke, his voice grew lower pitched and soon returned to his usual male baritone.

"What sort of dick was it, Frank! Tell me!" Walter said. As he spoke, he too, started to sound less like the adult male he was and more like the hot gymnast he appeared to be. "Wait! That's it! The more like the girls we think, the more we sound like them! It's concentration based!"

"So what does this exactly mean?" it came from Frank.

"Hmm... Ah, I think I got it! So, tell me...."