Noise Detection in audio signal -

i have 1 min clip of audio signal sampled @ 44.1khz. spectrogram of same provided below.

there of background noise in clip

the link original clip provided here

what best possible way either a) reduce background noise or b) enhance speech signals only.

also, how can noise identified in spectrogram? generating spectrogram have used following commands

[x, fs] = wavread('cpp_part.wav'); spectrogram(x,512,400,512,fs,'yaxis');