I recently found that the installed text to speech agent no longer works with mIRC out of the box. This is a result of backwards compatibility problems with a microsoft component and also the lack of a text to speech engine with windows.
So how do you now get your mIRC to talk.
There is a good help page here :- http://www.mirc.com/agents.html
However the links to the files you need are broken so I shall provide links to the 2 files you need in step 3
The first is spchapi.EXE version 4.0 filesize is 828KB and it may be found here :-http://www.microsoft.com/downloads/details.aspx?FamilyID=7D13964C-06FD-4BF9-B49C-814FAA6A86EA&displaylang=en
The second is the Lernout & Hauspie TruVoice Text-to-Speech (TTS) Engine. Depending upon the language you wish to enable the filesize is 2-3MB and it may be found here :-http://www.v3mail.com/download/ttsengines.htm
Downloading and installing these 2 files will enable the full speech properties of the Merlin agent that ships with mIRC, without them you will only get text balloons out of him.
You may think that merlin is an uneccessary distraction well in speech mode so do I. the reason that I looked into him was to help a user who wanted to improve his english. However I found that when he was enabled in text balloon mode for queries only he was quite useful. He allowed me to read queries and decide if they required a response without me having to open the query windows.
I had absolutely no issues with these files and hope anybody who needs them will have the same.