I'm tired of graphics in small screen. I believe millions would agree with me. So no GUI is not a big deal.

Hmm... perhaps a braille terminal with two-four characters on the bottom of a wrist watch?

Yes, I noticed my friend using voiceover in situations that would normally warrant silent operation. White cane allows him some slack. Am attempting a universal product. So, a two part workaround:

1) use voiceover when headphones are connected

2) use tapic engine for clues about marked events

This year, pervasive Bluetooth headsets make 1) a lot more viable.

Because sighted users may use headsets a bit less, have also included graphic cues.

"VUI" - first time I've heard of a VUI. Like it.

We developed Vorail for bind people. it turns out they really like it. I've finished a prototype on Android to examine the idea of "Sound Virtual Reality". Apart fro the fancy name, it plays multiple streams of audio on different direction (left, front, and right), and allows users to swipe on screens to "move" around.