Trying to understand how the brain does this has occupied auditory neuroscientists since the 1950s, when British cognitive scientist Colin Cherry coined the term “the cocktail party problem”. Early experiments asked volunteers to listen to two speeches simultaneously but repeat only one aloud. Cherry found that listeners could follow the pre-selected message remarkably well, despite both speeches playing at the same time, one in each ear. In contrast, they recalled very little of the other message.
These experiments laid the foundation for selective attention research. However, only in the past 15 years have scientists studied this phenomenon in experiments reflecting the complex ways we listen in the real world, using non-invasive technology like electroencephalography (EEG) to track brain activity as speech unfolds.
In a 2014 study, neuroscientists found that within 200 milliseconds of hearing someone speak, the brain favours the conversation being focused on over all other noise. This prioritised attention shows up most markedly in secondary brain areas such as the superior temporal gyrus, which piece together sounds into meaningful speech.