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Re: artifact in spectrogram created using Raven

Subject: Re: artifact in spectrogram created using Raven
From: "Avocet" madl74
Date: Mon Jul 16, 2012 4:37 pm ((PDT))
> one of the first things I noticed when I opened it up was a strange
> white space underneath the song, which roughly correlates with
> amplitude and pitch.

Laura,

I haven't heard the track, but what the spectrogram (aka audiogram aka
sonogram) shows is that the recording has been "compressed" or put
through an automatic level control which is the same thing. The
birdsong comes out at about the same level as the background instead
of being a lot louder. The recording will "pump" in level up and down
as the birdsong comes and goes.

The way to avoid this is to record at what sounds a low level and
bring the volume up later which you can do with digital recording. If
the recording level bar is bobbing along at about mid point, that is
plenty. You should be able to adjust the level with your editor.

Compression, limiters, and auto level controls ruin a recording and
can't be reversed. They also lose the original sound level patterns
which are important with displays like spectrograms.

David

David Brinicombe
North Devon, UK
Cogito cogito ergo cogito sum - Ambrose Bierce







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