Gregory Kunkel wrote:
> I solved that problem in my bird song trap for the last twelve
>years by feeding the output of my mic preamp into an equalizer. I
>originally used one scavenged from an old hi-fi system but eventually
>bought a mono ten band equalizer, the AudioSource EQ10.1 - -Ten Band
>Equalizer, at Crutchfield I believe about 8 years ago. It worked well
>for this purpose.
>
>I usually cut off the 30,50,125 and 250 Hz bands and boosted the 4,8,
>and 16Khz bands. I am mainly interested in warblers.
That's a crude but effective way of making a single high-pass filter
by using seven octave-band filters--but there's a cost. The frequency
response of the boosted frequencies will not be flat. There will be
three broad peaks from the three boosted frequencies, with valleys
probably several dB deep between them. The technique may be adequate
for your process but a real high-pass is flat in the high frequencies.
The difference would be most audible with broad-band sounds. Human
perception seems to be very forgiving of warped frequency response in
birdsong.
-Dan Dugan
|