🎧 Procedures to label files



Install Audacity


Audacity is a free, open-source audio editing and recording software and will be used to visualize and label the acoustic files.

You can download it here  https://www.audacityteam.org/  .

  • Use Audacity to visualize and analyse the files


Open the file in Audacity



1- The following window should appear:



Download the audio files from OneDrive.
A folder with several audio files will be shared with you using a specific link. To use them in Audacity you might download them to your computer.



2- To open a wav file, go to File → Open→ Select wav.file

By default, Audacity first opens the waveform of the audio file:


3- Open the spectrogram mode (the sound sources are labelled in this mode):


After selecting the spectrogram, a window like this should appear:



4- Amplify the file

Select the complete file and amplify with the default settings: it is always necessary to amplify to hear/visualize some specific sounds.

In the spectrogram select:

CTRL+ A > EFFECT > VOLUME AND COMPRESSION> AMPLIFY. By default, Audacity will propose the amplification (dB), just press “Apply”:


( Note: In the following picture, you will see in the Amplification box 0 value. Don´t worry with this value and assume the value that shows in your window, as each acoustic file will have different values to amplify. Always accept the default values showed by audacity. You only need to do this process once.)




Film Frames Below is a tutorial on "How to open an Audio file in Audacity" to help you



5- Analyse the File

To better visualize the natural sounds (such as whistles, squeaks, etc) it is recommended to zoom in the axis of time in the spectrogram. A window with 1 second of unit of time is a good resolution to identify the natural sounds (as it follows on the next spectrogram).

You can zoom the time here (blue arrow):

You can click several times on the magnifying glass icon until your time scale is similar as follows.


You can zoom in the frequency as well: to do so, right-click on the frequency scale, a menu will open, and you can choose the type of zoom you would like to apply:


When you open the audio file in Audacity, by default, it only shows a certain range of frequencies. To visualize the high frequency sounds you need to Zoom out on the spectrogram to visualize. You can do that in the “Zoom to fit “option to display the full range frequencies, as explained in Point 7.2.

To listen the high frequency sounds and also natural sounds (for example pings, gulps, squaks, creaks, burst-pulse, it's recommended to reduce the play speed. You can do on the button at the bottom of the window:


Film Frames Below is a tutorial on "How to navigate in the Audacity" to help you




6-Starting labelling

Select the sound in the spectrogram with cursor:


After selecting, press CTRL+ B in the selected window and the label tab will be displayed at the bottom, where you can write the correct label category: (in this case “WHI”). Do this for all the acoustic events visible in the file.

IMPORTANT RULES!
All acoustic events must be labeled.
•Do not forget, all labels must be written with the exact codes given for each class.
•Labels can overlap.
•Events that are apart more than 1 sec must be labelled separately. Events that are apart less than 1 sec can be labelled together.
•The start and end time of the label should be as close as possible to the start and end time of the acoustic event to increase precision.

Film Frames Below is a tutorial on "how to label each sound"





7- After you label all the recognizable sounds, you need to save the labels in a file.


Audacity allows you to save all the labels in one single .txt file. You need to save this file with the same name as the .wav file and at the end add your name initials.
Example: if the file name is “6335.230909074958.wav”, and your name is Joana Maria, save it as “6335.230909074958JM.txt”.

To change the .txt file name, you can do it directly in the label tab (as shown next) or upon saving.

Press “Select” in the label tab:

IMPORTANT
Before export the labels, you also need to make sure that you include the frequency information of each labels. On the superior Tab select: Edit-⟶Preferences and a small window should appeared like in this picture

In the import/Export tab select "Extended (with frequency ranges)" press ok.(You only need to do this step once. However, if you deleted audacity you need to do this step again.)


To export the .txt file, select File → Export other→ Export Labels:



To do not lose track of the files already labelled, it is recommended to save the .wav file and .txt file in the same folder (you may save the Audacity project as well in your computer if you need to consult afterwards).
Save the files with your initials at the end of the filename, without using any special characters such as -, _, or /.
Upload the .txt files to your specific folder in One Drive (Sharepoint). For example, if you are Joana Maria, you should have a folder named "Labers_JM", in the One drive. (If not please contact Carolina Ramos).