Basic requirements for a headphone check:

If you want to perform a headphone check on a platform without using javascript (e.g., Qualtrics, Gorilla.sc), you can build your own from the following outline.

• The sound files needed for the headphone check can be downloaded from: https://github.com/mcdermottLab/HeadphoneCheck/tree/master/assets

• A demo of a minimal headphone check is provided by the code in https://github.com/mcdermottLab/HeadphoneCheck#code-overview. To run this demo, copy-and-paste the HTML code into a text file and save it with a .html extension; e.g. headphoneCheckDemo.html. When opened in a web browser, this file should load a basic headphone check demo.

Outline of a headphone check:
The javascript code in this repository merely provides a prettified, extensible interface to the task outlined below.

• Have the participant calibrate their computer's volume to a loud but comfortable level using assets/noise_calib_stim.wav as the calibration sound.
• There are six other files in the assets/ folder, named like assets/antiphase_HC_IOS.wav. Each of these files corresponds to a single headphone check trial, consisting of three sequential tones. The participant is asked to listen to each file/trial (only once), then "Simply judge WHICH SOUND WAS SOFTEST (quietest) -- 1, 2, or 3?".
• The correct response for a trial/file is coded in the corresponding filename. See https://github.com/mcdermottLab/HeadphoneCheck/blob/master/HeadphoneCheck.js#L99 for the pattern.
• Participants that respond correctly to fewer than 5/6 trials are screened from analysis and/or prevented from continuing the experiment.