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## Whale Song Labeling

Recordings of whale songs contain trills and moans. Trills sound like series of clicks. Moans are low-frequency cries similar to the sound made by a ship's horn. You want to look at each signal and label it to identify the whale type, the trill regions, and the moan regions. For each trill region, you also want to label a few selected signal peaks.

Start by loading a data set that includes two recordings of whale songs. The signals are called `whale1` and `whale2` and are sampled at 4 kHz. `whale1` consists of a trill followed by three moans. `whale2` consists of two moans, a trill, and another moan.

```load labelwhalesignals % To hear, type soundsc(whale1,Fs), pause(22), soundsc(whale2,Fs)```

Bring the signals into Signal Labeler:

1. Start Signal Analyzer and drag the signals to the Signal table.

2. Select the signals and add time information. On the Analyzer tab, click Time Values, select `Sample Rate and Start Time`, and enter the sample rate, `Fs`.

3. With the signals selected, click Label on the Analyzer tab.

Define labels to attach to the signals. Labels can be of three types:

• Attribute labels define signal characteristics.

• Region-of-interest (ROI) labels define signal characteristics over regions of interest.

• Point labels define signal characteristics over points of interest.

Each label can have one of four data types:

• Logical labels can be either true or false.

• Categorical labels can belong to any one of a set of categories that you specify.

• Numeric labels can have any numeric value.

• String labels can have any value represented by a string.

Any label can have any number of sublabels. Sublabels themselves cannot have sublabels.

For the whale song signals:

1. Define a categorical attribute label to store whale types. Call it `WhaleType`. The possible categories are blue whale, humpback whale, and white whale.

2. Define a logical region-of-interest (ROI) label that is true for moan regions. Call it `MoanRegions`.

3. Define a logical ROI label that is true for trill regions. Call it `TrillRegions`.

4. Define a numeric point label to capture trill peaks. Call it `TrillPeaks`. Set this label as a sublabel of the `TrillRegions` label.

To define each label, click Add Definition on the Label tab. To define the sublabel, select the `TrillRegions` label in the Label Definitions browser, click Add Definition ▼, and select `Add sublabel definition`.

Enter the following values in the fields in the dialog box that appears for each signal label or sublabel definition. Leave the Default field empty in each case.

`$\phantom{\rule{3.6em}{0ex}}\begin{array}{c}{\phantom{\rule{0.2777777777777778em}{0ex}}}_{}\\ \begin{array}{ccccc}{Label\phantom{\rule{0.2777777777777778em}{0ex}}Name}_{}& Label\phantom{\rule{0.2777777777777778em}{0ex}}Type& Label\phantom{\rule{0.2777777777777778em}{0ex}}Description& Data\phantom{\rule{0.2777777777777778em}{0ex}}Type& Categories\\ WhaleType& Attribute& Whale\phantom{\rule{0.2777777777777778em}{0ex}}type& categorical& \left\{\begin{array}{c}blue\\ humpback\\ white\end{array}\\ MoanRegions& ROI& Regions\phantom{\rule{0.2777777777777778em}{0ex}}where\phantom{\rule{0.2777777777777778em}{0ex}}moans\phantom{\rule{0.2777777777777778em}{0ex}}occur& logical& ---\\ TrillRegions& ROI& Regions\phantom{\rule{0.2777777777777778em}{0ex}}where\phantom{\rule{0.2777777777777778em}{0ex}}trills\phantom{\rule{0.2777777777777778em}{0ex}}occur& logical& ---\\ TrillPeaks& Point& Trill\phantom{\rule{0.2777777777777778em}{0ex}}peaks& numeric& ---\end{array}\\ {\phantom{\rule{0.2777777777777778em}{0ex}}}_{}\\ \phantom{\rule{0.2777777777777778em}{0ex}}\end{array}$`

You can export the signal definitions you created to a MAT-file by clicking Export. A dialog box appears that prompts you for a file name. At any point you can import signal definitions stored in a MAT-file by clicking Import.

### Label Signal Attributes

The songs in the data are from two blue whales. Set the `WhaleType` values for both signals:

1. Select `WhaleType` on the Label Definitions browser.

2. Click Label ▼ and select `Label Signals`.

3. In the dialog box that appears, verify that both `whale1` and `whale2` are selected and that the Value field is set to `blue`. (If you do not specify a default value in a categorical signal label definition, Signal Labeler sets the label to the first category specified in the definition.)

4. Click OK.

Plot the `whale1` signal by selecting the check box next to its name. Signal attributes appear both in the Labeled Signal Set browser and under the time plot.

### Label Signal Regions

Visualize the whale songs and label the trill and moan regions.

• Trill regions have distinct bursts of sound punctuated by silence. `whale1` has a trill centered at about 2 seconds.

• Moan regions are sustained low-frequency wails. `whale1` has moans centered at about 7 seconds, 12 seconds, and 17 seconds.

Label the signals one at a time:

1. On the Plot column of the Labeled Signal Set browser, check the box next to the signal name to plot the signal.

2. To label a moan, on the Label Definitions browser, select the `MoanRegions` label definition.

3. Click Label ▼ and select `Label Plotted`. A shaded region appears, framed by an animated dashed line. (The animated frame indicates the region is active.) Move and resize the active region until it encloses a moan region. For better label placement, you can go to the Display tab and choose a zoom action or activate the panner.

4. Click Accept, press Enter, or double-click to label the ROI. The region changes to a gradient of the signal color. If you do not specify a default value in a logical label definition, Signal Labeler sets the label to `true`.

5. Repeat the procedure for the other two moans.

6. To label a trill, on the Label Definitions browser, select the `TrillRegions` label definition. Label the trill region using steps 3 and 4.

7. Before labeling the second whale song signal, remove the first whale song signal from the plot by clearing the check box next to its name in the Labeled Signal Set browser. If you have the two signals plotted when you label a region or point, Signal Labeler associates the label with both signals.

The label viewer axes show the locations and widths of the regions of interest. They also show the value assigned to each region.

### Label Signal Points

Trill regions have distinct peaks that correspond to bursts of sound. Label three peaks in each trill region. Because trill peaks are sublabels, each one must be associated with a particular `TrillRegions` label.

Label the signals one at a time:

1. On the Plot column of the Labeled Signal Set browser, check the box next to the signal name to plot the signal. Also check the box corresponding to the trill region whose peaks you want to label.

2. On the Label Definitions browser, select `TrillPeaks`.

3. On the toolstrip, under Value, enter `1`, corresponding to the first peak.

4. On the Labeled Signal Set browser, select the trill region. The trill region becomes active and is framed by an animated dashed line.

5. Click Label ▼ and select `Label Plotted`. The trill region is framed by a solid line, and an animated dashed (active) line appears for the point being labeled.

6. Move the active line until it crosses the signal at a peak of your choice. For better label placement, you can go to the Display tab and choose a zoom action or activate the panner.

7. Click Accept, press Enter, or double-click to label the peak. The dashed line changes to a solid line of the same color as the signal.

8. Repeat for two more peaks, entering `2` and `3` to identify them.

9. Before labeling trill peaks for the second whale song signal, remove the first whale song signal from the plot by clearing the check box next to its name in the Labeled Signal Set browser.

The label viewer axes show the locations of the points of interest and the value assigned to each point.

Plot the two signals to see a summary of their labels in the Label Viewer. Expand the labeled signal set hierarchy in the Labeled Signal Set browser to see details for all the labels. (To expand the hierarchy, right-click any signal in the browser and select `Expand All`.) For each signal, plot the first moan region and the third trill peak that you labeled.

### Edit Signal Label Values

At any point, you can edit any signal label using the Labeled Signal Set browser. To edit an attribute label, select it, right-click, and select Edit. For example, if you discover that the second whale is actually a white whale, you can select the `WhaleType` attribute for `whale2`, right-click, select Edit, and, on the dialog box that appears, select `white` from the drop-down menu.

If you want to edit the value of an ROI label or a point label, you can modify the value in the dialog box. To modify the location of an ROI label or a point label, you can modify the location fields in the dialog box. Alternatively, you can:

1. Plot the label by checking the box next to its name.

2. Select the label.

3. Move the region or point in the time plot when it becomes active.

### Export Labeled Signal Set

Export labeled signals by saving your labeling and exporting the new `labeledSignalSet` object. Click the Save Labels button on the toolstrip. In the dialog box that appears, give the name `whalesongs` to the labeled signal set. Clicking the OK button gets you back to Signal Analyzer. See Signal Labeler Import and Export Behavior for more information on how Signal Labeler exports labeled signal sets.

On the Signal table, select `whalesongs` and right-click to export it to a file called `Whale_Songs.mat`.