Knowledge Base

Background

Call definitions are used to detect calls in your recordings. See how to Add a call definition. The signal is detected as "call" when it fulfills the conditions set by the call definition parameters.

• Call Name: The name of the call definition. The same name will be given automatically to all calls detected based on that definition.
• Call Color: The color for this call definition (and the detected calls).

Parameters

• Frequency Low (Hz): The lower frequency limit. Signals with frequency below that value are ignored.
• Frequency High (Hz): The higher frequency limit. Signals with frequency above that value are ignored.
• Min Amplitude: The value of amplitude below which the signal is not included in the call.
• Min Duration (ms): The minimum duration of the call.
• Max Duration (ms): The maximum duration of the call.
• Min Gap (ms): The shortest time allowed between the stop of one call and the start of the next one. If two events matching the other parameters are found at less than the minimum gap, they are considered as one call.

Add a Call Definition

There are three ways to define a call:

• Select a call in the spectrogram and define a call.
• In the Call Detection screen, click the Add button and enter the call parameters. See Adjust a Call Definition.
• In the Call Detection screen, click Edit, then load a call template that was saved previously. See Load a Call Template.

Adjust a Call Definition

At least in some cases, selecting a rectangle around a call in the spectrogram does not lead to detection of similar calls as expected. For example, calls in the spectrogram that are a bit shorter than the minimum duration estimated when drawing the rectangle around a call will not be detected.

To Adjust a Call Definition

For all parameters:

1. Click on a call definition in the Call Definition list, then click the Edit button. Make the necessary changes and click OK.
2. Click Detect calls in this recording to detect the calls with the new definition. Note that clicking this button also updates the calls detected with other call definitions.

For the call definition name:

• Double-click the cell under Call Definition and rename the frequency range if necessary (that is important especially if you change the frequency limits).

For the frequency range:

• Drag the top or bottom side of the rectangle to select a higher or lower high frequency limit.

Note: Changing the frequency limits by dragging the rectangle top/bottom sides does not result in changing the call definition name (frequency label on the spectrogram). You have to do that manually.

For duration:

• Drag the left/right sides of the rectangle to change the minimum duration of the call definition.

Notes

• Editing the frequency limits does not result in changing the call definition name (frequency label on the spectrogram). You have to do that manually.
• You can save the call definition as a template to use it to search for calls in other experiments. In the Save as template field, enter a name for your template and click Save.

Load a Call Template

To apply a call definition to the current recording that was saved previously as a template, also in experiments other than that currently open.

Procedure

1. Under Recording, select the recording in which you want to detect calls based on an existing definition.
2. Click the Add button.
3. In the Edit Call Definition window, click the Load Call Template button.
4. Select a call template and click OK.
5. The Add Call Definition window is updated with the values stored in the imported template.
6. Edit the call definition (optional), then click OK.
7. The new call definition is appended to the Call Definition list.
8. Click Detect calls for this recording to detect the calls based on the call definition.

Call Templates

You can use a call template to detect calls in one or multiple recordings based on information that you obtained from other recordings (or experiments).

Definition

A call template is a container of one call definition. A call template includes the following information:

• Template Name
• Call Name
• Color
• Frequency lower and higher limits
• Minimum Amplitude
• Minimum Duration (ms)
• Maximum Duration (ms)
• Minimum Gap (ms)

Save a Call Definition as a Template

To save a call definition that can be used to detect calls in multiple experiments.

Procedure

1. Define a call.
2. When necessary, adjust a call definition.
3. Click the call definition name in the Call Definition List, and click the Edit button.
4. In the Edit Call Definition window, next to Save as template, enter a name for that call template.
5. Click Save.
6. Click OK.

Note

The call templates are saved in the call_defs.txt file located in C:\ProgramData\Noldus\UltraVox. Do not edit this file.

Detected Calls List

Contents

• Detected Calls: The name of the call definition used to detect that call. See Call Definitions.
• Color: The color of the call definition the call belongs to.
• Duration (ms): Duration of the detected call. This equals Stop time – Start time.
• Start Time (s): The start time is back-calculated when a number of samples above the Min amplitude (set in the call definition) have been found that exceed the Min duration (set in the call definition). From this time (tm) the Min duration is then subtracted to obtain the Start time.
• Stop Time (s): The stop time is back-calculated when a number of samples with low amplitude values (that is, below the Min amplitude in the call definition) have been found that exceed the Min gap time set in the call definition. From this time (tg), the Min gap time is subtracted to obtain the Stop time.
• Freq at Max Amp (Hz): The frequency at which the amplitude is the highest in that call.
• Mean Amplitude: The mean amplitude of a call is calculated as the sum of the amplitude of all points inside the call rectangle with an amplitude above the specified Min amplitude limit (in the call definition), divided by the number of points found. White background points in the spectrogram are generally not included as they would reduce the mean amplitude to a meaningless low value. This means also that mean amplitude is always higher than (or equal to) the Min amplitude limit.

Source: UltraVox XT 4 - Calls, Noldus Information Technology