This survey will test your ability to detect a digital audio watermark embedded in music files.
Digital audio watermarks hide extra information in an audio signal, usually for copyright enforcement purposes. The watermarks are designed to be inaudible, but necessarily add some distortion to the original audio.
The information below is meant to familiarize you with the sound qualities of the watermark before taking the test. Take your time with this material before you begin answering questions.
The following sample demonstrates a greatly exaggerated version of the watermark applied to a noise signal. The watermark starts after 2 seconds.
This distortion is visualized in the figure below, showing discrete blocks of noise that fluctuate in intensity over time.
In the following example, sample A is the original, and sample B is watermarked. The distortion is most audible during the loudest portion of the watermarked sample (B). Focus your attention on the voices of the choir. Listen for the rapid fluttering distortion, similar in character to the exaggerated example above. Switch back to the original sample (A) and notice that the fluttering is absent.
Below, you will find 16 groups of audio samples. In each group, you are presented with two versions of the same music sample. One contains a digital watermark, and the other does not. Switch back and forth between the two audio samples using the control buttons. Listen closely and try to determine which sample in each group contains a watermark. For best results, use headphones and take the test in a quiet environment.
Your score will be reported after you submit your answers.