android Making a VU-meter reacting to internal sounds

I wish to make a simple VU-meter element in android like this: http://ift.tt/1MwSkgU

However, I need it to react to an internal sound (more specifically to the Text-To-Speech Engine) and not to the microphone. Also I'm not quite experienced with making Android apps, so I'm not sure what's the best way to make the graphical element for it (photoshopping, ProgressBar, some xml magic, etc.).

How can I make it come to life? Thanks in advance!