Re:
Hello,
In fact, you could attempt to dampen out the background sound, or dominate vocal sound by altering the gain levels of the audio file's sound using an equalizer in an audio editing program, or bu using voice modification. Nero Wave Editor for example has several audio editing features, one which allows you to edit volumes across different frequencies and another allows you to alter output frequencis using 'Envelope Mapping'.
However, it's a tricky process, and takes many trials to hit the correct settings. There's also distortion possibilities and audio leakage, which more often than not, is unavoidable.