5.4.3. Creating a tier using the Audio Recognizer

As from version 3.6 ELAN offers the possibility to create tiers based on the output of an audio recognizer. A simple silence recognizer that comes with ELAN will show how to use an audio recognizer in ELAN. The recognizer can determine segments of silence in an audio signal based on examples given by the user. To use it for segmenting the audio first open the tab Audio Recognizer in the main ELAN window. Choose the appropriate recognizer from the pull down menu at the top of the tab, in this case Silence Recognizer (see also Figure 5.15).

Audio Recognizer

Figure 5.15. Audio Recognizer


The Silence Recognizer uses examples to determine what is silence and what is not. To give the recognizer an example first select a part of the audio that is silence (see also Section 7.1.6). Then click on Add Channel1 (or Add Channel2 if there is a second channel and that is the channel in focus) in the Audio Recognizer tab. The begin and end times of the example are shown in the list beneath the Add Channel buttons. By selecting a line in the list and clicking Remove an example can be removed. By double clicking a line in the list the associated time interval is selected in ELAN.

After giving sufficient examples, click on the Start button to start the recognition. During the recognition you can click Cancel to stop the recognition.

The result of the recognition is a segmentation in the Waveform Viewer for each channel for which an example is given. In the case of the silence recognizer the segments are either labeled 's' for the beginning of a silent segment or 'x' for the beginning of a non-silent segment. If you are not satisfied with the segmentation, you can change the examples or the duration parameters and start a new recognition.

[Note]Note

The second and subsequent runs of the audio recognizer can be several times faster than the first run. This is caused by the buffering the audio recognizer applies.

If the labeling is correct, you can create a tier with annotations reflecting the labeling in the Waveform Viewer. Click on Create Tier(s)... in the Audio Recognizer tab. On the tab Per Segmentation of the dialog window select the channel that has the segmentation you want to use from the pull down menu. In the table Select and configure segments first select the labels that must be included in the tier. If necessary, change the label by clicking in the third column of a label and enter a new label. Check the Number segments column if you want to number each annotation with a particular label. The number will be appended to the label. Finally, click the Create button to create the tier.

If all segment labels are to be used, open the All Segmentations tab instead of the Per Segmentation tab. On the All Segmentations tab you are only asked to select the channels for which a tier must be created. Again, clicking the Create button will make ELAN create the tier.

The controls we have seen so far are common for all recognizers. There are also controls that are specific for a recognizer. These controls can be found in the right half of the Audio Recognizer tab. In the case of the silence recognizer there are two sliders: Minimal Silence Duration and Minimal Non Silence Duration. When using another recognizer, these sliders are replaced by the controls implemented by that recognizer.

To learn more about creating and adding other recognizers, please read the relevant section on the Source Release Notes page (http://www.lat-mpi.eu/tools/elan/src-release-notes.html).