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 development of selective attention has also been examined. Jones and Moore for instance, studied how well children across various age groups could hear and respond to a target sound when it was masked by other auditory stimuli. They discovered that 9– to 11-year-old children became as adept as adults at paying attention only to the target sound and filtering out the masking sound (2015, p. 366). This shows that research on selective auditory information is important to continue as it allows us to better understand our world. Prevalence 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