Use the Accessibility palette to specify custom text for an object that a Microsoft Active Accessibility (MSAA)- compliant screen reader reads as it passes through the form. If custom screen reader text is available for the object, the screen reader will read the custom text and not the tool tip.
You can also change the default order in which the screen reader searches for text to read on an object-by-object basis, and you can turn off screen reader text for any object.
See also 

Accessibility palette