Audio Systems: Help with audio problems, notch filters, stereo microphone

Question
i was  editing an event shot in a bar. sorry but i don't have the details about
the cam used and its was my first project so I'm not that familiar with fixing
the audio
problem was the audio doesn't sound natural, my client want the audio to be
clear.
because the result was the voice of the people in the footage was really rough
I'm using a software soundtrack pro in  my mac
is there a filter or something that would improve the voice?
thanks for reading and hope you can answer my problem

Answer
The microphones build in to most camcorders are not high quality. Since some of the manufacurers try to pack in a stereo microphone, it can make it even worse if you are in a noisy room. Camcorders have built in compressors to prevent distortion of sound. Compressors decrease the dynamics by making low sounds, sound louder and loud sounds lower. Most of the time if high sound quality is desired a simultaneous feed is run to hard disc of some audio recording device. That doesn't help you now, so the options you have are as follows: If the mac can strip away the sound and then re insert in in sync with the video then you can use an audio re-mastering program such as Sound Forge, Audacity, etc to process the sound. You will need to experiment with equalization, notch filters, mixing or eliminating channels, expansion in order to make the sound more pleasing.  I am a seasoned engineer and I would have difficulty with a project like that. It is doable.

Good Luck