https://phys.org/news/2013-02-human-fourier-uncertainty-principle.html
Human hearing beats the Fourier uncertainty principle
«The results have implications for how we understand the way that the brain processes sound, a question that has interested scientists for a long time. In the early 1970s, scientists found hints that human hearing could violate the uncertainty principle, but the scientific understanding and technical capabilities were not advanced enough to enable a thorough investigation. As a result, most of today’s sound analysis models are based on old theories that may now be revisited in order to capture the precision of human hearing.
"In seminars, I like demonstrating how much information is conveyed in sound by playing the sound from the scene in Casablanca where Ilsa pleads, "Play it once, Sam," Sam feigns ignorance, Ilsa insists," Magnasco said. "You can recognize the text being spoken, but you can also recognize the volume of the utterance, the emotional stance of both speakers, the identity of the speakers including the speaker’s accent (Ingrid’s faint Swedish, though her character is Norwegian, which I am told Norwegians can distinguish; Sam’s AAVE [African American Vernacular English]), the distance to the speaker (Ilsa whispers but she’s closer, Sam loudly feigns ignorance but he’s in the back), the position of the speaker (in your house you know when someone’s calling you from another room, in which room they are!), the orientation of the speaker (looking at you or away from you), an impression of the room (large, small, carpeted).
"The issue is that many fields, both basic and commercial, in sound analysis try to reconstruct only one of these, and for that they may use crude models of early hearing that transmit enough information for their purposes. But the problem is that when your analysis is a pipeline, whatever information is lost on a given stage can never be recovered later. So if you try to do very fancy analysis of, let’s say, vocal inflections of a lyric soprano, you just cannot do it with cruder models."
By ruling out many of the simpler models of auditory processing, the new results may help guide researchers to identify the true mechanism that underlies human auditory hyperacuity. Understanding this mechanism could have wide-ranging applications in areas such as speech recognition; sound analysis and processing; and radar, sonar, and radio astronomy.
"You could use fancier methods in radar or sonar to try to analyze details beyond uncertainty, since you control the pinging waveform; in fact, bats do," Magnasco said.
Building on the current results, the researchers are now investigating how human hearing is more finely tuned toward natural sounds, and also studying the temporal factor in hearing.
"Such increases in performance cannot occur in general without some assumptions," Magnasco said. "For instance, if you’re testing accuracy vs. resolution, you need to assume all signals are well separated. We have indications that the hearing system is highly attuned to the sounds you actually hear in nature, as opposed to abstract time-series; this comes under the rubric of ’ecological theories of perception’ in which you try to understand the space of natural objects being analyzed in an ecologically relevant setting, and has been hugely successful in vision. Many sounds in nature are produced by an abrupt transfer of energy followed by slow, damped decay, and hence have broken time-reversal symmetry. We just tested that subjects do much better in discriminating timing and frequency in the forward version than in the time-reversed version (manuscript submitted). Therefore the nervous system uses specific information on the physics of sound production to extract information from the sensory stream.
"We are also studying with these same methods the notion of simultaneity of sounds. If we’re listening to a flute-piano piece, we will have a distinct perception if the flute ’arrives late’ into a phrase and lags the piano, even though flute and piano produce extended sounds, much longer than the accuracy with which we perceive their alignment. In general, for many sounds we have a clear idea of one single ’time’ associated to the sound, many times, in our minds, having to do with what action we would take to generate the sound ourselves (strike, blow, etc)."