I don't understand, however the file that must be accessible is this one like on the demo site:
http://demo.storejextensions.org/screenreader/plugins/system/screenreader/screenreader/libraries/tts/proxy.php
If the server answers with a 404 the audio won't work, opening in the browser you can test it.
Check the mod_security option of the local server and htaccess if there is a disallow for direct php file access, but don't ask me because i'm not expert in server configuration.
If not use a working live server to setup the plugin.
