  How is information processed in the brain during perception? Mechanistic
insight is achieved only when experiments are employed to test formal or
computational models. In analogy to lesion studies, phantom perception may
serve as a vehicle to understand the fundamental processing principles
underlying auditory perception. With a special focus on tinnitus -- as the
prime example of auditory phantom perception -- we review recent work at the
intersection of artificial intelligence, psychology, and neuroscience. In
particular, we discuss why everyone with tinnitus suffers from hearing loss,
but not everyone with hearing loss suffers from tinnitus. We argue that the
increase of sensory precision due to Bayesian inference could be caused by
intrinsic neural noise and lead to a prediction error in the cerebral cortex.
Hence, two fundamental processing principles - being ubiquitous in the brain -
provide the most explanatory power for the emergence of tinnitus: predictive
coding as a top-down, and stochastic resonance as a complementary bottom-up
mechanism. We conclude that both principles play a crucial role in healthy
auditory perception.
