Noises on—How the Brain Deals with Acoustic Noise.

Simple Summary: The listening brain must resolve the mix of sounds that reaches our ears into events, sources, and meanings. In this process, noise—sound that interferes with our ability to detect or understand sounds we need or wish to—is the primary challenge when listening. Importantly, noise to one person, or in one moment, might be an important sound to another, or in the next. Despite the many challenges posed by noise, however, human listeners generally outperform even the most sophisticated listening technologies in noisy listening environments. Because extracting noise from the sound stream is a fundamental process in listening, understanding how the brain deals with noise, in its many facets, is essential to understanding listening itself. Here, we explore what it is that the brain treats as noise and how it is processed. We conclude that the brain has multiple mechanisms for detecting and filtering out noise, and that incorporating cortico-subcortical 'listening loops' into our studies is essential to understanding this early segregation between noise and signal streams. What is noise? When does a sound form part of the acoustic background and when might it come to our attention as part of the foreground? Our brain seems to filter out irrelevant sounds in a seemingly effortless process, but how this is achieved remains opaque and, to date, unparalleled by any algorithm. In this review, we discuss how noise can be both background and foreground, depending on what a listener/brain is trying to achieve. We do so by addressing questions concerning the brain's potential bias to interpret certain sounds as part of the background, the extent to which the interpretation of sounds depends on the context in which they are heard, as well as their ethological relevance, task-dependence, and a listener's overall mental state. We explore these questions with specific regard to the implicit, or statistical, learning of sounds and the role of feedback loops between cortical and subcortical auditory structures. [ABSTRACT FROM AUTHOR]