  Whether animal or speech communication, environmental sounds, or music -- all
sounds carry some information. Sound sources are embedded in acoustic
environments that contain any number of additional sources that emit sounds
that reach the listener's ears concurrently. It is up to the listener to decode
the acoustic informational mix, determine which sources are of interest, decide
whether extra resources should be allocated to extracting more information from
them, or act upon them. While decision making is a high-level process that is
accomplished by the listener's cognition, selection and elimination of acoustic
information is manifest along the entire auditory system, from periphery to
cortex. This review examines latent informational paradigms in hearing research
and demonstrates how several hearing mechanisms conspire to gradually eliminate
information from the auditory sensory channel. It is motivated through the
computational need of the brain to decomplexify unpredictable real-world
signals in real time. Decomplexification through information loss is suggested
to constitute a unifying principle of the mammalian hearing system, which is
specifically demonstrated in human hearing. This perspective can be readily
generalised to other sensory modalities.
