Dichotic listening (DL)

Dichotic listening (DL) is a noninvasive technique for studying brain lateralisation, or hemispheric asymmetry, to reveal left hemisphere dominance in language processing.

In fact, in many people, the left hemisphere of the brain is dominant in language processing. This means that it is primarily responsible for understanding and producing language.

The connection between dichotic listening, auditory selection, and the cocktail party effect primarily concerns how the brain processes auditory information in complex listening situations, such as a noisy parties or an environment where many voices are present at the same time.

While dichotic listening is the process of Dichotic listening and selective auditory attentioneceiving different auditory stimuli to each ear at the same time or quickly one after the other, auditory selection refers to the brain's ability to focus on a specific sound or voice in a complex acoustic environment. It is the process that allows us to distinguish and focus on a desired sound while ignoring or suppressing other background noise. This process is essential to be able to understand and interact in noisy environments. Finally, the Cocktail Party Effect is an example of auditory selection: it is a common phenomenon in crowded or noisy social situations. It occurs when you are able to focus on a specific conversation or sound, such as a person's voice, even if there are many other conversations or sounds in the background.

The Cherry Model, Broadbent Model and Treisman Attenuation Model are three important theories in the field of auditory and visual perception. There are other models (such as Active Search Model and the Cross-Modal Influence Model) but these three theories are the main ones.

• The Cherry Model, also referred to as the 'Selective Filter Theory,' was initially introduced by Donald Broadbent in 1958. It was subsequently expanded upon and further developed by the cognitive scientist Colin Cherry, who is historically associated with the theory.

This is a theory of auditory perception: according to its hypothesis, our brain becomes a selective filter and searches for an auditory input channel, automatically ignoring other input.

This model explains how people are able to concentrate on a single voice in complex listening situation (cocktail party problem).

• The second model is known as the Attenuative Filtering Model or 'Broadbent Model', after the scientist Donald Broadbent who theorized it in the 1950s. It is still a theory of auditory and visual perception but, unlike Cherry's model, it is based on the hypothesis that the brain filters the information arriving from unselected channels in an "attenuated" way; unlike the previous model, the information is not completely eliminated but reduced in intensity.

• The latest model, proposed by Anne Treisman in 1964, is a variant of the Broadbent model. This model is based on the concept of "attenuation" and works in the same way as the previous one. Furthermore, according to Treisman, attention can be selectively shifted from one channel to another based on the relevance of the information (for example, if you are focused on a discussion but hear your name in the distance, your brain redirects your attention towards the source of the sound).