AUDACITY . A QUICK GUIDE to filters and editing 32-Bit float files.

To change between Waveform and Spectogram i Audacity push the small triangle close to the filename UP LEFT!

About Audacity

Audacity is a free editing software you safely can download and use. You can cut files, remove low-pitch rumble, remove bands of sounds like crickets or funny machinery with equalizer and you lower or risen volume before uploading as mp3 or wav for further use+++. A package of loads of fun playing around with files up to 24 or even 32 bit float. See for more information, NB we do not take any responsibility for software you download!


Editing birdsongs and calls in the free software Audacity is quite simple when you get to know the basics of the layout. Personally I prefer to work in Spectogram view so I can see the noise, pings, handling noise, stomach rumbling and other unwanted parts of the recording. Push the small triangle up left and change between waveform and spectogram. Through this simple guide I hope you will be more familiar with this powerful tool and in the end publish more (and less noisy) birdsounds from around the world at or Macauley Library ++

I use a PC for this guide, but it works more or less the same way on a Mac!

For further insight in setup of Audacity; read the article by Volker Arnold.


Linux/Ubuntu users: because **High Pass Filter** (among other filters) is a

**plug-in** which should ship with the Audacity package but does not show in the list of filters. It is found under

**Effects** right at the bottom in **Plug-ins 1-15**.* If you cannot find it there, first check if you have the file on your system under usr/share/audacity/plug-ins. It is called highpass.ny.* If you do not have it, then make sure you have Audacity version 2.1.2 (PPA) or higher – see << for more info – and you may need to install the extra filters from

**Nyquist** –* If you do have it, then in Audacity, click on **Effects

–> Add/Remove Plug-ins** and install from there.

First you need to open a recording via File> Open

My 8 minute long testfile is a Bluethroat Luscinia luscinia from Northern Norway singing, the frequency range of the song starts at about 2 Khz and all the shady area below are noise from wind and rivers nearby. The birds mimics loads of birds in this recording!


Stereo view of Bluethroat song. Click to change Khz-scale up/down

Open your file and then you will get a screen looking something like this:

NB My Audacity is a Norwegian version!

On the Y-axis (left vertical) is the frequency range from 0 Hz to ab 12 000 Hz (12 Khz), To change/zoom the frequency-range push left button on the axis above 0k, shift-push left same place for opposite zooming of the scale.
TOP scale is time in seconds, first 6 seconds of recording shown. NB! In Edit>Preferences you can preset the scale you want to start with when opening Audacity. I have set: Max 9000 Hz, Min 0 hz Window type: Hamming, Window size 4096.

The horizontal X-axis is in seconds and minutes, this total recording is ab 8 minutes long, I will work with only a part of this. To select a part of the recording set your pointer (arrow) on a place along the X-axis and push left mouse-button. Then hold and drag the mouse to the right or left to define the area you like to edit. TIP: On either side of the greyed out area a Hand will appear, drag the sides of the marked area with holding left button and release! The screen will now look like this:

Next step is to define how much of the bottom noise to filter, following the the left axis we can see the song starting at ab. 2 Khz so some of the noise below can be edited without affecting the song itself. I first choose to use Effect>High Pass Filter, set it to 1500 Hz and level 6 db. This will give you a soft start close up to maximum level without destroying the song itself. Black painted line indicates the area filtered.

To Zoom in/out choose the +/- OR choose the selection tool (selected area ONLY) or view the entire recording (Right)

In this case it’s already quite smooth all the way to the bottom line (0-100 Hz) but often traffic, boats, engines, fans etc in the neigbourhood creates a hum that is annoying, and we can choose to filter that even further. I choose High Pass Filter, set 12 db and 1200 Hz. Now you will see it turns white (blank) and there is NO sound at all in the bottom part! To strengthen the effect: Ctrl + R

NB! This could create a less natural result, so test it out before publishing! Listen to the results in the bottom!

NB! Normally 150-400 Hz and 6-12 db is sufficient for a nice result! This could reduce background a little but does not take away the surrounding environment completely!

Noise reduction filter: This is normally enough and you can save the file, but sometimes White noise (wind, traffic or running water etc.) makes the birdsong less attractive, in Audacity there is a filter «Noise reduction» that can reduce this noise. If used wrong and too harsh it can destroy the quality of the song itself so be careful. I seldom set level higher than 4 or 5! First step is to drag an area with ONLY noise appearing, you do not want to filter the song itself. Then choose Filter/Effect > Noise reduction and set the level to 5 in step 1 «Get Noise Profile» , push OK. Then mark the targeted area again (CTRL + A will mark the whole recording) and push Ctrl + R and it will do the job!

Below you will see the the final result and the uppermost noise is a bit lighter and less prominent, this without destroying the original song made by the bird!

NB! The Xeno-canto team do not recommend this filtering, but for listening to a noise-free recording it really helps! Use this with caution!!

You now have to export the final result to your hard-disc or other media. Again mark/select the edited area and choose:

File > Export> Export Selected Audio The box will ask you where to put the file and the format (MP3 or wave (WAV)). Push Save and you will get a new box –

Choose: File>Export>Export Selected Audio to save marked area! Choose MP3 or WAV.
NB! If you choose «Export as MP3 or..WAV» it saves the whole file!

The Metadata.
Here you name the recording f.ex. Bluethroat male singing, Troms County, Label a Album; Birds of Norway, Year, Additional info; Weather, recorder used, Mics etc. Then push Save and the new file will appear in your chosen folder. NB The latest version of Audacity (Version 2.3.2 or later) comes with already installed MP3-converter (LAME).

REDWING Low-cut filter and Noise reduction
Highpass-filter (see bottom of filtered sections .6 to 1.6 sec)
Noisereduction 5dB start midst of Redwing call


In 2019 the first recorder came with ability to record in 32-bit float and edit it in Audacity and several other software packages. We show here an example from Adobe Audition of a Wigeon male completely messed up and you can pull it down with no loss of quality, see and hear the examples how it works.

The Right part of the Sonogram is a typical destroyed sound-file, in 24Bit this is a lost case! But in 32Bit float this can be saved easily, do NOT play with full volume!! !
Normalized and destroyed example of Wigeon call, and do NOT play with full volume!!
Same recording and Right part is now pulled down to same level as the Left song-burst, Quality is now remained!
Lower part ab. 450 Hz has been filtered with High Pass filter in Audacity, the dark bar is made to visualize the two bursts.
HighPass 450 Hz in Audition
A final short round in Audacity, Noise reduction 5 dB and 700 Hz HighPass-filter 6 dB