[Accessibility] Audio-tactile maps on smart phones

[robert]

Audio-tactile maps on smart phones

I would like to have an OSM map accessible for visually impaired users
with a program that makes sounds when you move your finger over the map.
A different sound for the different map items (roads, water and
buildings) and that speaks the names on the map. By moving your finger
over the map  you know what is where on the map.
You know where your finger is on the device and you hear what is under
your finger so you can make an image in your mind what is where.

If the map is centered around you (with GPS) you can find out what is
around you and where to go.

You would not need special hardware, just a smart phone with gps and
touchscreen and one that knows its orientation. 
By adapting one of the open source  programs that use OSM maps (like
Navit) you would not need to completely write a navigation and map
viewing program. You would just need to develop a plugin/module for such
a program to satisfy our needs.

I have also posted the idea in the Navit forum  on sourceforge.net
http://sourceforge.net/projects/navit/forums/forum/512959

Does anyone have ideas about  how to organize and program (write the
code) this?

Thanks,

Robert