Edward Colin Cherry, known as Colin Cherry, (1914 – November 23, 1979) was a British electronic engineer and cognitive scientist whose main contributions were in focused auditory attention. He began his career in engineering and his interest in telecommunication led him to realize the need for engineers to understand how people perceive and behave in order to develop technology, such as telephones and computers, that are user friendly. This led to his interest in visual and auditory perception as well as speech.
Cherry is best known for his work on the "cocktail party effect," the human ability to follow a single conversation while many other conversations are proceeding at the same time. This is a relatively easy task for human beings in a normal live environment. However, the mechanism by which we process the incoming sounds and selectively attend to the appropriate speaker is still not clearly understood and it remains a very difficult problem for computers.
Cherry's work on the "cocktail party effect" inspired over half a century of research. The results of such research, in a wide range of areas, continue to be of great relevance and value today.
Colin Cherry was born in St Albans, England in 1914. He was educated at St Albans School. In 1932 he began work as a laboratory assistant with General Electric Company Research Laboratories. During his time there he also took evening classes at Northampton Polytechnic (now City University) gaining his B.Sc. in engineering in 1936.
He was then appointed to the research staff at General Electric and continued working there until 1945. From 1939 to 1945, during World War II, he was also engaged in war work with the Ministry of Aircraft Production, researching radar at the Radar Research and Development Establishment in Malvern, Worcestershire and engaged in flying trials.
After the war, he was appointed assistant lecturer at the University of Manchester. In 1947 he moved to Imperial College, London as a lecturer in electrical engineering. In 1952 he took sabbatical leave, spending six months in the United States at Massachusetts Institute of Technology (MIT), where he worked with Jerry Weisner and Norbert Weiner and others interested in communication. He returned to Imperial College, where he was awarded a doctorate in 1956 and became a Reader in Telecommunication. In 1958 he was appointed to the Henry Mark Pease Chair of Telecommunication.
In 1978 he was awarded the Marconi International Fellowship. He decided to use this to write a book, provisionally entitled A Second Industrial Revolution? He completed only three chapters and the Preface before his death. One of his former students, William E. Edmondson, collected his material and completed it, publishing it as The Age of Access: Information Technology and Social Revolution. He also used the award to sponsor a conference on "The Foundations of Broadcasting Policy," which was held in May 1980 six months after Cherry's death.
Cherry published numerous academic papers and several books. His most influential books include On Human Communication (1957) and World Communication: Threat or Promise (1971).
Colin Cherry died on November 23, 1979 in London, aged 65.
Cherry's training, including his degrees, was in engineering. His first teaching positions were in Electrical engineering, both at the University of Manchester and Imperial College London. He published numerous papers based on his research on electrical circuits before moving on to communication engineering.
However, he became dissatisfied with engineering as "applied science," and became interested in design and the need to know more about human factors in order to design useful products. In particular, his sabbatical at MIT in 1952 introduced him to the thinking of linguists, like Roman Jakobson, and psychologists such as George Miller. He was much influenced by their work, and realized that without understanding human perception it was not possible to design telephones or other auditory and visual devices that are easily used by people.
Engineers were focused on how to transmit a signal without distortion rather than how to use the signal to communicate the information. Cherry realized that without understanding the human factor, human perception, engineers could not design their products effectively. For example, the study of waveforms does not tell the engineer whether the listener correctly understands the auditory message nor whether the television viewer can see the picture easily. Cherry's research then began to include psychological factors, such as perception and speech.
In the early 1950s Cherry began to study the situation of air traffic controllers who received messages from pilots over loudspeakers in the control tower. Hearing the intermixed voices of many pilots over a single loudspeaker made the controller's task very difficult. His famous paper published in 1953 defined and named this problem the "Cocktail party effect" or "Cocktail party problem" since since the underlying processes are still not completely understood.
Human beings have the ability to focus their listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. The effect enables most people to talk in a noisy place. For example, when conversing in a noisy crowded party, most people can still listen and understand the person they are talking with, and can simultaneously ignore background noise and conversations. Live sound includes numerous variables that allow people to easily differentiate the various sounds and their sources. However, when the sounds are recorded, or broadcast through a loudspeaker to the air traffic controllers, the distinctions between speakers become much less clear and it is hard to single out a particular sound source. In recorded sound the type, location, and movement of the microphone(s) lead to a representation of the sounds, a new version of the sound events. In this new version, the location and movement of those speaking, as well as the volume and tone of their voices, are not reliably represented in the same way as live sound.
Cherry conducted experiments where subjects were asked to listen to two different messages from a single loudspeaker at the same time and try to separate them, repeating one but not the other, known as a "shadowing" task. His work revealed that our ability to separate sounds from background noise is affected by many variables, such as the gender of the speaker, the direction from which the sound is coming, the pitch, and the rate of speech. When the messages were similar in these characteristics subjects were unable to complete the task successfully. He also used dichotic listening tasks in which the two messages were still presented to the participants simultaneously, but one to each ear, using a set of headphones. In this situation, subjects had no problem separating the two messages, even when spoken by the same person.
Cherry also found that people recalled even the shadowed message poorly, suggesting that most of the processing necessary to shadow the attended message occurs in working memory and is not preserved in the long-term memory. Performance on the unattended message was, of course, much worse. Participants were generally able to report almost nothing about the content of the unattended message. They could not be sure that the language was English; in fact, a change from English to German in the unattended channel usually went unnoticed. They were mostly not aware that the speech in the unattended ear was being played backwards, although some reported that it sounded rather strange. However, participants were able to report that the unattended message was speech rather than non-verbal content like a tone, and when the speaker changed from male to female.
Donald Broadbent extended Cherry's work with additional experiments and suggested that "our mind can be conceived as a radio receiving many channels at once." He developed a "filter model" in which the brain separates incoming sound into channels based on physical characteristics (such as location), using a filter. This theory provides an explanation of the "cocktail party" phenomenon, since the voice that a person is attending to has different physical characteristics from those of other people in the room. No semantic analysis is necessary to differentiate them. It also explains both Cherry's and Broadbent's experimental findings—unattended messages are rejected by the filter and thus receive very little processing. Later findings, however, led him to recognize that the filtering was more complex than just based on physical characteristics and that some content of the message was analyzed prior to filtering.
Colin Cherry has been called a pioneer of cognitive science although he would never have described himself that way. He promoted the use of television in education, being one of the first to suggest its use in the classroom, as well as the idea of televising government proceedings.
His work on the "Cocktail party problem" triggered research that has continued for more than half a century in a wide range of areas. This phenomenon is still very much a subject of research, from the psychological process of selective attention in humans studied by Donald Broadbent, Anne Treisman and others, to computer implementations (where it is typically referred to as source separation).
Source separation in digital signal processing involves several signals that have been mixed together and the objective is to find out what the original signals were. Sound engineers continue to refer to Cherry's work on the Cocktail party problem, noting that the human brain can handle such auditory source separation problems (although the neural mechanism in human brains that supports this process is still unclear), but it is a very tricky problem in digital signal processing.
In 1987, Imperial College London inaugurated the Colin Cherry Memorial Lectures on Communication in Cherry's honor. Presented by world-famous speakers from a variety of fields including Seymour Papert, Douglas Adams, David Puttnam, Nicholas Negroponte, and Steven Pinker, these lectures attract capacity audiences.
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