I'm looking for liberies to *.wav, or to speech

[ptpwjp]

I'm looking for library having such functions or procedures:
to stick several *.wav,
to do loud *.wav, to change speed, tone, or something similar.

I want to used searched library in Visual Basic.
The searched library must be free for individual user.

To stick several *.wav by using play in VB isn't interested for me,
but if there isn't another way, I accept it.

Or, I looking for way of changing the voice (or install new voice)
in Microsoft library system.speech,
but only with possibility to use normal polish way of speaking.