Audio File

This file is trigger (t=0)

Check this checkbox if you want this file to be the time trigger for this stimulus. If this file is marked as a time trigger, the moment the playback of this file starts, the time will start to be measured ("the stopwatch starts"). This app defaults to setting a timed trigger on each LAST running file within the stimulus. See the Timeline tab. In principle, you don't need to worry about triggers except in 2 cases:

You don't want the last running file within the stimulus to start the time trigger, you want it to start timing when some previous file within that stimulus starts playing. Such research models are relatively rare, but they certainly exist.
Multiple files are launched in parallel at the same time. As it is always possible that your operating system will not be able to fully accomplish this, mark which of these files takes precedence. The application will "start the stopwatch" only when this file starts playing.

Only one file within each stimulus can start the time trigger. If you do not explicitly set a time trigger, the application will automatically set the default time trigger for the file that is played last within the stimulus.

This application enables parallel playback of multiple audio-image files. Parallel playback = two or more files start at the same point in time. If you use parallel playback, then you need to explicitly mark which file is the trigger. Mainly due to the delay of the non-real-time operating system, minor differences in the playback start of 2 or more files are always possible, even though they have the same playback start time set. If the image file and the audio file start at exactly the same time, and both are last within the stimulus, then the audio file takes precedence over the image file, ie the audio file will be set as the trigger.

Start playing an audio file (ms):

Enter the time in milliseconds when you want this audio file to start playing. This time starts running (t=0) from the moment when the interstimulus interval ended. Thus, the end of the interstimulus interval, after the presentation of the previous stimulus, represents absolute zero (t=0). Be sure to check out the timeline table tab. For example if you type 2000, this audio file should start playing 2 seconds after the interstimulus interval has ended. If you enter 0, this audio file should start playing immediately after the interstimulus interval has ended (after the previous stimulus). It is possible to enter the same value for multiple audio files as this application allows multiple audio files to be played simultaneously. Mainly due to the delay of the non-real-time operating system, minor differences in the playback start of 2 or more files are always possible, even though they have the same playback start time set. If you check Set as default, the new entered value becomes the default for each new audio file.

Audio Volume by percentage:

If you set 0 (default), application will not change the audio volume. Enter the desired audio volume by percentage in the range from 0 percent to 100 percent. Do not enter percentages, but only numbers in the range 0..100. We show the original description of the MASTER_GAIN parameter from this link:

		Represents a control for the overall gain on a line.

		Gain is a quantity in decibels (dB) that is added to the intrinsic decibel level of the audio signal--that is, the level of the signal before it is altered by the gain control. A positive gain amplifies (boosts) the signal's volume, and a negative gain attenuates (cuts) it. The gain setting defaults to a value of 0.0 dB, meaning the signal's loudness is unaffected. Note that gain measures dB, not amplitude. The relationship between a gain in decibels and the corresponding linear amplitude multiplier is:
		
		linearScalar = pow(10.0, gainDB/20.0)

		The FloatControl class has methods to impose a maximum and minimum allowable value for gain. However, because an audio signal might already be at a high amplitude, the maximum setting does not guarantee that the signal will be undistorted when the gain is applied to it (unless the maximum is zero or negative). To avoid numeric overflow from excessively large gain settings, a gain control can implement clipping, meaning that the signal's amplitude will be limited to the maximum value representable by its audio format, instead of wrapping around.

The PRG application converts this MASTER_GAIN parameter into percentages within the maximum possible range. So, here you enter values in percentages of the maximum possible range of the MASTER_GAIN parameter (0-100%).

If you check Set as default, the new entered value becomes the default for each new audio file.

Warning: Always make sure headphones/speakers are set to a low volume to avoid damage to hearing or equipment.

Number of repetitions (playback) of this audio file:

Enter here the desired number of repetitions of this audio file (default = 1). The number of repetitions does not affect the trigger. If this audio file is a trigger, the stopwatch always starts at the start of the first playback of this audio file. If you check Set as default, the new entered value becomes the default for each new audio file.

Adjust control for the left-right positioning of the audio signal between two stereo speakers:

normal - two speakers. Play centered. Playback on both channels.
left speaker only. Play left channel only.
right speaker only. Play right channel only.

Note that the "left" channel may or may not be the same as the "left" speaker. The same applies to the "right" channel.

If you check Set as default, the new entered value becomes the default for each new audio file.

If you use a wav file that does not contain data for both channels (stereo), and at the same time select left speaker only or right speaker only an error SysErr=1000 (or more) will occur and that stimulus will be declared invalid.

For creating audio files, we recommend the Audacity application. In order for the left/right channels to work, you must record a wav file on both channels within the Audacity application:

Audacity 3.4.2 => File => Export Audio => Audio Options Channels => Stereo

You must respect the warning Allowed range of values is. Otherwise, the newly set value will be discarded without any warning when closing this dialog.

If you do not want to save the changed settings within this dialog, you must explicitly click on the Cancel button when closing this dialog. Closing this dialog with "x" (Close) or Save and Close , automatically saves all (changed) values.

You can display this Dialog Box in one of these ways:

Double click on the some audio file in the Stimulus List
Select the desired audio file in the Stimulus List and click on the Properties button on the Bottom toolbar