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This is the reverse of the question asked here. I have a lot of audio recordings and I would like to increase the volume of the peaks without changing the troughs.

So amplify is no good, I guess some sort of 'reverse' normalise might work (does that even exist?). Any solution needs to be automatic, I have hundreds of hours of audio which I would like to do this to. Any suggestions are greatly appreciated, thanks.

EDIT

The recordings are natural soundscapes collected in the forest, with a fairly small omnidirectional microphone. I would like to make the birdsong louder and the background hiss/noise of the wind quieter. Apologies for my ignorance, I am very new to recording and editing.

  • 'Normalise' won't affect anything except the global volume. An expander is what you need, though which one will really depend on your source material & what you need to achieve. We would need more info or a sample of your start-point with a clearly-defined goal. – Tetsujin Aug 30 '16 at 18:30
  • How handy are you with a volume fader? – Marc W Aug 30 '16 at 23:10
  • @Tetsujin, I've added some information in my original question. I'm very new to all this, sorry if I've missed details. Suggestions for an expander and pointers for use would be greatly appreciated. – EcologyTom Aug 31 '16 at 6:25
  • Expander is a reasonable idea, but I'd be tempted to use something like Isotope RX... I won't add it as an answer, though, just as a link to their product page. Please be sure to be sitting down when you get to the prices ;) – Tetsujin Aug 31 '16 at 15:18
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    Have you tried using a high-pass filter? I found that this can cut out a lot of background noise with birds, since the bird sounds are very high-pitched. The "Noise Reduction" option works quite well, too. Find a section (one or two seconds long) with no birds, just wind, to use as the source. Might work, if you haven't already tried these ideas. – Phil Freihofner Sep 1 '16 at 16:29
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To use an expander, first of all you'll need to understand upward and downward expansion.

Downward Expansion

This increases dynamic range by turning down the signal when it falls below the threshold. A gate is an example of downward expansion.

This also means that downward expansion could in fact end up reducing dynamic range instead. This will happen if the signal is cut off (like a gate is able to) instead of just turning it down.

Downward expansion can be used for a variety of things, such as lowering the tail of a kick drum or bass, creating more separation between notes or hits. An upward expander could achieve something similar in certain cases, but from a different perspective.

Upward expansion

This increases dynamic range by turning up the signal when it exceeds the threshold.

This is useful for making existing peaks pop out even more, and is exactly what you're looking for in your question.

Free VST Plug-in

You can download a free VST expander to use as a plug-in in Audacity.

For example there is one called Modern Expander from Antress Modern Plugins available for free download here: http://antress.blogspot.co.uk/

  • Thanks @SimonBosley. That one is windows only, but I've found some that are suitable for Mac. Do you know of any good tutorials that I could look at so I can learn how to use an expander? I'm very new to all this so it is a bit confusing... – EcologyTom Aug 31 '16 at 9:02
  • Hi @EcologyTom which one did you find in the end? I'll update my answer to include a Mac option in case others end up on this page. I don't have a go to resource for expanders, I'll update my answer to include upward and downward expansion to get you started. – Simon Bosley Aug 31 '16 at 11:48
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    the Readme file in the Antress download lists only Windows operating systems, but no worries. Your information gives me a good starting point to understanding the process. Thanks for the advice! – EcologyTom Aug 31 '16 at 16:05
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You could try working with an expander, which is the reverse of a compressor and increases the dynamic range.

  • is there an expander in Audacity? Or a tool which will have that effect? The compressor in Audacity seems pretty similar to amplify – EcologyTom Aug 30 '16 at 15:00

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