Dichotic listening (DL)

Last update on Sep, 25, 2023

What is the dichotic listening task?

Dichotic listening is a test that uses a particular technique to analyse cognitive and brain functions. It is used in psychology and neuroscience to study hemispheric asymmetries, attention and consciousness. Performing the test is very simple: the test, in fact, consists of playing two simultaneous and different acoustic sounds through headphones, one in the right ear and the other in the left.

Auditory integration

The test is based on the concept of "auditory integration", i.e. the auditory system must process different signals in each ear at the same time and unite them in a process called auditory integration.

Binaural separation

In some situations, during the test the patient will have to ignore the signal sent to one ear while focusing on the signal perceived by the other ear.

This happens thanks to binaural separation: our hearing perceives the direction and position of sound, differentiating the time and intensity of the sounds that reach each ear. These differences are processed by the brain to determine the position of sounds in space. It is a phenomenon that is fundamental to the perception of direction and it is used in advanced audio technologies and hearing tests.

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Different types of Dichotic listening tests

Emotional Factors

Emotional states, such as anxiety or stress, can affect a person's ability to focus on a specific ear during the dichotic test. For example, a person with high anxiety may have difficulty focusing on a specific ear due to hyperactivation of the nervous system or emotional concerns.

Manipulation of Voice Onset Time (VOT)

Voice onset manipulation involves altering the timing of auditory input, specifically adjusting when a voice or sound begins. For example, you can delay the onset of a voice relative to a background sound or vice versa. This manipulation can be used to study how the brain perceives and processes auditory signals based on the temporal order of sounds.


Dichotic listening tests are also used in neuroscience researc, specifically in assessing language lateralisation. These tests can help explore the neuroanatomical structures involved in individual language perception and its asymmetry.

Language Processing

Dichotic listening can also be used to test for hemispheric asymmetry of language processing, examining how the brain processes language and whether there are significant differences in language lateralisation between individuals.

To better understand these definitions, it is best to explain the meaning of "cerebral laterization": The human brain is divided into two hemispheres, the right hemisphere and the left hemisphere, which are connected to each other through the corpus callosum. Each hemisphere has specific cognitive functions. Cerebral lateralisation refers to the fact that some functions are more dominant in one hemisphere than the other.


In the context of schizophrenia, individuals with specific subtypes of this illness may experience different auditory lateralisation patterns.

A study utilizing the dichotic listening test, with a focus on specific subtypes of schizophrenia, such as paranoid and undifferentiated, revealed that paranoid schizophrenics favour the left hemisphere.

Dichotic listening and left-hemisphere dominance

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.

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Dichotic listening and selective auditory attention

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.

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Historical background and scientists

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).

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