Selective auditory attention
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Selective auditory attention or selective hearing is a type of selective attention and involves the auditory system of the nervous system. Selective hearing does not involve the sounds that are not heard. However, it is characterized as the action in which people focus their attention on a specific source of a sound or spoken words. The sounds and noise in the surrounding environment is heard by the auditory system but certain parts of the auditory information are processed in the brain only. Most often, auditory attention is directed at things people would like to hear. The increased instances of selective hearing can be seen in family homes. A common example would be a mother asking her child to do something before he or she can enjoy a reward. Mother may say: “James, you can have an ice-cream after you clear your room.” And James replies: “Thanks mom! I needed that ice-cream.” Selective hearing is not a physiological disorder but rather it is the capability of humans to block out sounds and noise. It is the notion of ignoring certain things in the surrounding environment. Over the years, there has been increased research in the selectivity of auditory attention, namely selective hearing.
Through observations, one would realize that it is the reward that is heard almost all the time. The mind does not process the auditory information about the chore. It is basically the filtration of positive pleasant information. If the child was not physically impaired in hearing, he would have heard the whole sentence being said. It has puzzled parents, as well as psychologists, the way the child’s mind can selectively hear the things that they want to hear and leave out unpleasant tasks.
Researchers have been studying the reasons and possibilities of this missing link in the procedure of the selectivity of auditory information in the brain. In 1953, a cognitive scientist from England, Colin Cherry, was the first person to discover a phenomenon called the cocktail party problem. He suggested that the auditory system can filter sounds being heard. Cherry also mentioned that the physical characteristics of an auditory message were perceived but the message was not semantically processed. Another psychologist, Albert Bregman, came up with the auditory scene analysis model. The model has three main characteristics: segmentation, integration, and segregation. Segmentation involves the division of auditory messages into segments of importance. The process of combining parts of an auditory message to form a whole is associated with integration. Segregation is the separation of important auditory messages and the unwanted information in the brain. It is important to note that Bregman also makes a link back to the idea of perception. He states that it is essential for one to make a useful representation of the world from sensory inputs around us. Without perception, an individual will not recognize or have the knowledge of what is going on around them. While Begman's seminal work is critical to understanding selective auditory attention, his studies did not focus on the way in which an auditory message is selected, if and when it was correctly segregated from other sounds in a mixture, which is a critical stage of selective auditory attention. Inspired in part by Bregman's work, a number of researchers then set out to link directly work on auditory scene analysis to the processes governing attention, including Maria Chait, Mounya Elhilali, Shihab Shamma, and Barbara Shinn-Cunningham.
Recently, researchers have attempted to explain mechanisms implicated in selective auditory attention. In 2012, an assistant professor in residence of the Neurological Surgery and Physiology in the University of California San Francisco examined the selective cortical representation of attended speaker in multiple-talker speech perception. Edward Chang and his colleague, Nima Mesgarani undertook a study that recruited three patients affected by severe epilepsy, who were undergoing treatment surgery. All patients were recorded to have normal hearing. The procedure of this study required the surgeons to place a thin sheet of electrodes under the skull on the outer surface of the cortex. The activity of electrodes was recorded in the auditory cortex. The patients were given two speech samples to listen to and they were told to distinguish the words spoken by the speakers. The speech samples were simultaneously played and different speech phrases were spoken by different speakers. Chang and Mesgarani found an increase in neural responses in the auditory cortex when the patients heard words from the target speaker. Chang went on to explain that the method of this experiment was well-conducted as it was able to observe the neural patterns that tells when the patient’s auditory attention shifted to the other speaker. This clearly shows the selectivity of auditory attention in humans.
The prevalence of selective hearing has not been clearly researched yet. However, there are some that have argued that the proportion of selective hearing is particularly higher in males than females. Ida Zündorf, Hans-Otto Karnath and Jörg Lewald carried out a study in 2010 which investigated the advantages and abilities males have in the localization of auditory information. A sound localization task centered on the cocktail party effect was utilized in their study. The male and female participants had to try to pick out sounds from a specific source, on top of other competing sounds from other sources. The results showed that the males had a better performance overall. Female participants found it more difficult to locate target sounds in a multiple-source environment. Zündorf et al. suggested that there may be sex differences in the attention processes that helped locate the target sound from a multiple-source auditory field.
Selective hearing is not known to be a disorder of the physiological or psychological aspect. Under the World Health Organization (WHO), a hearing disorder happens when there is a complete loss of hearing in the ears. It means the loss of the ability to hear. Technically speaking, selective hearing is not “deafness” to a certain sound message. Rather, it is the selectivity of an individual to attend audibly to a sound message. The whole sound message is physically heard by the ear but the idea is the capacity of the mind to systematically filter out unwanted information. Therefore, selective hearing should not be confused as a physiological hearing disorder.
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- Chang, E.F., & Mesgarani, N. (2012). Selective cortical representation of attended speaker in multi-talker speech perception. Nature, 485, 233-237.
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