Following a mention in Yuuki Aoi's 2channel thread, I took a look at episode 15 of Jewelpet Tinkle, in which she has a small role.
And what I heard was probably the highest voice I have ever heard in anime, but pure and clear and not at all annoying. It is a real mouse-like squeak, but one with tremendous strength and energy in it, and in which the words are clear. What an instrument Ao-chan has.
This variation of her voice is something new: a fan on 2channel said he watched the whole show without realizing Ao-chan was in it until the credits rolled. Although maybe he should have recognized her: that voice couldn't have been anyone else. Even Kaneda Tomoko's voice isn't that high.
She plays a mouse-like creature called Ameri. Her best voiced passages are following 7:43 and 14:32. Don't be surprised if the incredibly high sound calls all the dogs from around the neighborhood:
Here are audio clips of her voice from the episode:
Ameri is one of a trio of jewelpets (small magical animals) who compete in a sweets bake-off with the star jewelpets: Ruby (Saitou Ayaka), Sapphi (Sasaki Nozomi), and Garnet (Hirano Aya).
The sweets bake-off is, of course, a reference to the show Yumeiro Patissiere, in which Ao-chan stars. Perhaps Jewelpet's move to Saturday morning, so it is no longer so direct a competitor with Yumepati on Sunday mornings, allowed it to go ahead and make reference to the other show.
I might expect Yumepati (a far superior show, in my opinion) to return the favor at some point. Sasaki Nozomi has already had an occasional role in the show, as Ayukawa. Here is a pic of Sapphi (Sasaki Nozomi, left) and Ameri:
I hadn't watched an episode of Jewelpet for a while, and I was impressed by how unlike herself Hirano Aya sounded as Garnet. I don't think I could have identified the voice if I didn't know already that it was her. Here are Garnet (left), Sapphi (centre) and Ruby (right):
In her blog today, Ao-chan posted another picture of her new cat Eimi and apologized for being a fond parent. She excused herself for not having posted in a while, saying she was in "report hell" at university.