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Each dot represents a subject’s performance on Task 5 (simultaneously measuring the duration and frequency of a sound), with temporal acuity on the x-axis and frequency acuity on the y-axis. All dots within the black rectangle beat the Fourier uncertainty principle. Credit: Oppenheim and Magnasco ©2013 American Physical Society
(Phys.org)—For the first time, physicists have found that humans can discriminate a sound's frequency (related to a note's pitch) and timing (whether a note comes before or after another note) more than 10 times better than the limit imposed by the Fourier uncertainty principle. Not surprisingly, some of the subjects with the best listening precision were musicians, but even non-musicians could exceed the uncertainty limit. The results rule out the majority of auditory processing brain algorithms that have been proposed, since only a few models can match this impressive human performance.
The researchers, Jacob Oppenheim and Marcelo Magnasco at Rockefeller University in New York, have published their study on the first direct test of the Fourier uncertainty principle in human hearing in a recent issue of Physical Review Letters. The Fourier uncertainty principle states that a time-frequency tradeoff exists for sound signals, so that the shorter the duration of a sound, the larger the spread of different types of frequencies is required to represent the sound. Conversely, sounds with tight clusters of frequencies must have longer durations. The uncertainty principle limits the precision of the simultaneous measurement of the duration and frequency of a sound.
To investigate human hearing in this context, the researchers turned to psychophysics, an area of study that uses various techniques to reveal how physical stimuli affect human sensation. Using physics, these techniques can establish tight bounds on the performance of the senses. An ear for precision To test how precisely humans can simultaneously measure the duration and frequency of a sound, the researchers asked 12 subjects to perform a series of listening tasks leading up to a final task. In the final task, the subjects were asked to discriminate simultaneously whether a test note was higher or lower in frequency than a leading note that was played before it, and whether the test note appeared before or after a third note, which was discernible due to its much higher frequency. When a subject correctly discriminated the frequency and timing of a note twice in a row, the difficulty level would increase so that both the difference in frequency between the notes and the time between the notes decreased. When a subject responded incorrectly, the variance would increase to make the task easier.
Read more at: http://phys.org/news/2013-02-human-fourier-uncertainty-principle.html#jCp
