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Audio Stimulus

An audio stimulus plays an audio clip.

Required Properties

type

  • Definition: The type of stimulus
  • Possible values: For audio stimuli, must be specified as audio
{
  "type": "audio",
  "content": "audio1.mp3"
}

content

  • Definition: A pointer to the underlying resource
  • Possible values: Must be the file name of the audio file (you will be prompted to upload the audio file)
  • Format support is dependent upon the participant's browser. See Tips tab for further information.
{
  "type": "audio",
  "content": "audio1.mp3"
}
  • mp3 tends to work well across our supported browsers and all major operating systems (Windows, Mac, and Linux). However, there is a chance that older Linux systems with older browsers will not support this format.
  • There are many ways of converting your audio stimuli to the desired format. For audio transcoding, check out fre:ac.

Optional Properties

autoplay

  • Definition: Whether or not to start playing the audio without participant action
  • Possible values: true or false
  • Default: true
  • Setting this option to false nullifies the delay parameter.
  • This parameter affects the audio when used as a choice response as well.
{
  "type": "audio",
  "content": "audio1.mp3",
  "autoplay": false
}

barrier

  • Definition: If set to true, all subsequent stimuli and responses will not be displayed until this audio clip finishes playing
  • Possible values: true or false
  • Default: true

{
  "type": "audio",
  "content": "audio1.mp3",
  "barrier": false
}
In trials using the above stimulus code, other stimuli and responses will be displayed at the same time as the audio plays.

{
  "type": "audio",
  "content": "audio1.mp3",
  "barrier": true
}
In trials using the above stimulus code, the audio will play before other stimuli and responses are displayed. This code is equivalent to code where the barrier property is not specified.

delay

Info

This property is used for presenting multiple stimuli on a trial in a sequence. To implement inter-trial intervals, see the delay parameter in trial templates instead.

Warning

The delaying of multiple stimuli on a trial does NOT have a chain effect. That is, the delay of any stimulus on a trial is always relative to the onset of that trial or the end of the last stimulus acting as a barrier.

  • Definition: Delay the onset of a stimulus by a certain number of seconds, relative to (1) the onset of a trial if there are no stimuli acting as barriers or (2) the end of the last stimulus acting as a barrier.
  • Possible values: A number in seconds (decimals are supported)
  • Default: 0 (no delay)

{
  "type": "audio",
  "content": "audio1.mp3",
  "delay": 0.3
}
The above code introduces a delay of 300 milliseconds.

  • This property is optional but recommended for an audio stimulus. If not set, the audio may appear to start abruptly on a new trial.

parent

  • Definition: If specified, then the properties of the specified stimulus will be inherited by this stimulus, unless a property of the same name is defined in this stimulus
  • Possible values: The name of another defined stimulus

"audio0":{
  "type": "audio",
  "content": "audio1.mp3",
  "delay": 0.3,
  "visible": false
}

"audio1": {
  "type": "audio",
  "content": "audio1.mp3",
  "parent": "audio0",
  "visible": true
}
Here, the audio1 stimulus inherits the delay property of audio0. audio1 does not inherit the visible property of audio0 because the stimulus definition of audio1 has its own specified visible property.

visible

  • Definition: Whether audio controls should be displayed. If set to false, the audio will play in the background
  • Possible values: true or false
  • Default: true
  • Do not set autoplay to false if the audio plays in the background only.
{
  "type": "audio",
  "content": "audio1.mp3",
  "visible": true
}

See Also

The Tokenized Audio Stimulus