11:27 video
Tilly, really makes a higher pitched sound when the different sensations are being used upon her, the softer side of things usually brings out a subtle sound, while when the sharper items are used it's a higher based sound that escapes her lips, as it was when I was using the Scruber Brush upon her skin.
When I mixing the softer and harder/sharper side(s) of things that's when the true sounds came escaping from Tilly.