The DOM And Screen Readers
http://juicystudio.com/article/dom-screen-readers.php

Lemon, Gez
Juicy Studio
2006

Abstract:

This article investigates a method of providing client-side form validation through the DOM, and ensures that it works as expected with screen readers. Modern screen readers work relatively well with scripting, but it's the extra steps required to inform screen reader users that the content has changed that needs addressing.