Caitlyn Jenner has made it clear that she's documenting every aspect of her transition as a transgender woman with her E! docu-series I Am Cait — and that includes some of her more vulnerable moments on camera yet.

Caitlyn previously admitted that it was "a little difficult" to see herself delivering her powerful speech at the 2015 ESPY Awards because of the sound of her voice. And now, in a new clip from an upcoming episode of the show, the Arthur Ashe Courage Award recipient is seen practicing her "female voice" for daughter Kim Kardashian.

In the new promo, Caitlyn explains how she'd try to put on a female voice when ordered room service when staying alone at hotels.

"I'd be sitting there in my room, all by my little lonesome and I'd go...okay, now, let's try to get my best feminine voice and call down, so they say 'Yes, ma'am.' I could never do it," she explains to Kim and a friend.

Kim then decides they should practice together, picking up her phone.

"I'll tell you if you get a 'yes, ma'am," she says. Caitlyn attempts to start in her best female voice.

"Yes, actually you can help me," she says, seemingly without any change in her voice.

"You sound no different!" Kim chuckles.

It's only a brief moment, but still somewhat heartbreaking: Caitlyn stays positive and laughs right along with Kim, but very clearly struggles with the reality.

"Women cannot relate to the whole voice thing...they don't see it as that important. It is that important," she explains later in a confessional.

“Up until now, I have totally isolated myself from the transgender community so I have a lot of catching up to do," Caitlyn previously wrote in a blog post earlier this month.

I Am Cait airs on Sunday at 8 PM ET. Will you be watching?

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