I am somewhat new to signal processing, but i'm hoping I can provide enough information in order to be pointed in the right direction.
I am working on analyzing the frequency spectrum of audio signal impulse response. A few of the impulses seem to have what looks like a large variable dc bias, and when performing a FFT they come back with very large DC values.
subtracting the mean did not help much in ways of correction. I think there may be other issues besides what appears to be DC but I am stuck.
The graphs below are plots of the FFT results from two signals - one with the warped dc bias, and one without. Hopefully this demonstrates better what may be happening to cause this. Any help is greatly appreciated.
both Signals are of the same sample length and FFT size
1st Image - FFT of good Signal, small-no DC value
2nd Image - FFT of problem Signal Large DC value