QtMultimedia not included

Hi everyone, I'm new here and I have a big problem.
I'm using qt libraries on ubuntu 12.04 system and I have compiled the 4.8.4 version with:

./configure -opengl
make
sudo make install

at the end of make execution, the program says to me that the libraries will be installed inside /usr/local/Trolltech/Qt-4.8.4 directory.
I made a simple hello world program with gui and it works very well, but when I use QAudioInput from QtMultimedia and I try to compile, the compiler gives to me: No such file or directory.
Code:

#include <QAudioInput> #include <QAudioOutput>
However the folder QtMultimedia inside /usr/local/Trolltech/Qt-4.8.4/include exists. Anyone knows how it is possible that the library is correctly installed but the compiler doesn't see it??

After that I tried to include the libraries path inside the .pro file:
Code:

INCLUDEPATH += -I/usr/local/Trolltech/Qt-4.8.4/include
it still does not link the library QAudioInput.
Please help me...