The latest version of Rasbian OS for the Raspberry PI does not include the pico tts (text to speech) engine. Well, the data file available but the utils and lib files are missing.

So, after some searching, I found a website in english, written by a german, who translated it from a french website, on how to download and compile the source. There is no date on the article, and the instructions are not that clear, so I have re-written them below:

The source code is available in the archive repository of the rasbian linux, so they must be added to the available source lists.

Edit the file /etc/apt/sources.list and add the following two lines at the end:

deb http://archive.raspbian.org/raspbian wheezy main contrib non-free rpi
deb-src http://archice.raspbian.org/raspbian wheezy main contrib non-free rpi

sudo nano /etc/apt/sources.list

Now refresh the repositories:

sudo apt-get update

So that we do not need to become root to build the package, install fakeroot:

sudo apt-get install fakeroot

To get all the additional packages (programs and libraries) that are needed by the pico engine, download them using build-dep:

sudo apt-get build-dep libttspico-utils

We need a place to download the source and compile (build) it. From your home directory:

cd
mkdir pico_build
cd pico_build

And now download the source:

apt-get source libtttspico-utils

This will download a number of packages which were then converted into directories. We need to build the source within the directory called svox-(version number). And then build:

cd svox-(version number)
dpkg-buildpackage -rfakeroot -us -uc

On a raspberry pi version 1 this will take considerable time, approx. 30 minutes or so.

When it has completed return to the above directory and there will be 3 deb files:

cd ../
ls *.deb

It is now time to install these programs:

sudo dpkg -i *.deb

and now you should be able to test the newly installed program:

pico2wave -w test.wav "Hello there from Pico!"
aplay test.wav

The instructions for pico2wave are here – http://manpages.ubuntu.com/manpages/precise/man1/pico2wave.1.html