wrote:
> Dear Experts,
>
> I seem to remember form my class at Cornell many years ago that secondary
> harmonics as shown on a spectrogram are really a result of the recording
> equipment and filtering these out of a cut will not degrade the final audio
> product.
> Actually, what I am trying to determine is if I filter a cut to reduce insect
> noise and this noise is also in the band where the secondary harmonic is,
> will
> I be significantly degrading the final audio product?
The harmonics can also not exist at all, but be a result of the math
that created the sonogram. In which case filtering will make no
difference at all. Not everything on a sonogram is really there. Not
only are there false "harmonics", but a lot of the spatter around a loud
call is not there either. Same with some "echoes".
The best way to find out what will happen is to do the filtering and
listen. If your software will not allow previews, then do it on a copy
of your sound file. Do a new sonogram too.
This is why I like filtering with Spark XL, I have the real-time
sonogram, and can immediately see what a filter change will do before
applying the entire filter set.
As far as the question if it's all real, that's really a judgment call.
Will removing the insects help more than removing the harmonic hinders.
In most cases where I need to do that here, removing the insects is
almost always the better way as they are so loud here. Judge it by
listening.
Note on listening, use as many different ways to listen as you can. Some
filtering is just fine in headphones and awful in speakers, or the
reverse is true.
Walt
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