May 31, 2009

Building the pod – episode 133

Filed under: !Podcasts,Building the Pod,Notch filter — Bruce Williams @ 12:00

This week, we look at the notch filter.


The waveform view of our sample audio


The spectral view of our sample audio.

Note the pink line running horizontally across the display between 5kHz and 6kHz


The spectral view of our sample audio, zoomed on the vertical scale

Here we can see that the offending tone is actually around 5700Hz


Spectral view after a 25dB cut

Notice how the line of the offending tone is approximately the same colour (and therefore the same amplitude) as the surrounding audio


Spectral view after a 15dB cut


Spectral view after a 45dB cut

Here, we can see that we’ve scooped out too much, which has left a hole in the audio we wanted to keep around the 5700Hz region

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