Hi,
Here are the steps to reproduce this bug:
1. Open a buffer and set the major mode to org-mode
2. Copy and paste the following into that buffer:
* First Heading
** Second Heading
3. Press Tab on the first heading so that you hear the ellipsis sound. Observe that the sub-heading called "Second heading" has disappeared.
4. Press C-e b. Observe that the heading is now spoken, even though it's hidden.
I'm not really sure what other text properties are ignored by emacspeak-speak-buffer. I just need the hidden text being respected for now, so that's the one I noticed.
Thanks!