Colin Cherry

Edward Colin Cherry, known as Colin Cherry, (1914 – November 23, 1979) was a British cognitive scientist whose main contributions were in focused auditory attention, specifically regarding the cocktail party effect. This concerns the problem of following only one conversation while many other conversations are going on around us. Cherry used shadowing tasks to study this problem, which involve playing two different auditory messages to a participant's left and right ears and instructing them to attend to only one. The participant must then shadow this attended message.

Cherry found that very little information about the unattended message was obtained by his participants: physical characteristics were detected but semantic characteristics were not. Cherry therefore concluded that unattended auditory information receives very little processing and that we use physical differences between messages to select which one we attend to.

Life

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.

Work

Cherry's work covered topics that ranged from electrical circuits, telecommunication principles, and the psychology of speech and hearing as his research interests changed over the years.

Engineering

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 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.

Telecommunication

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 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.

The classic problem that Cherry investigated is known as the "Cocktail party effect." This describes the ability of human beings 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. Nevertheless, if someone calls out their name from across the room, people will sometimes notice (the "own name effect").

In the early 1950s much of the early work in this area can be traced to problems faced by air traffic controllers. At that time, controllers 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. The effect was first defined and named by Colin Cherry in 1953. Cherry conducted attention experiments in which subjects were asked to listen to two different messages from a single loudspeaker at the same time and try to separate them. His work reveals 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. In cognitive psychology, dichotic listening is a procedure commonly used to investigate selective attention in the auditory system. In dichotic listening, two different auditory stimuli (usually speech) are presented to the participant simultaneously, one to each ear, normally using a set of headphones. Participants are asked to attend to one or (in a divided-attention experiment) both of the messages. They may later be asked about the content of either message.

Although most people spend their lives surrounded by many different types of stimuli, they cannot respond to or describe the majority of them. A practical example of this is found in the "cocktail party effect," described by Colin Cherry (1953) as the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. Cherry conducted experiments in which 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 based on the characteristics of the sounds, such as the gender of the speaker, the direction from which the sound is coming, the pitch, or the speaking speed. When the messages were similar in these characteristics subjects were unable to complete the task successfully.

Broadbent extended this work by devising what is known as the "dichotic listening" experiment. In these studies, subjects were asked to listen to and separate different speech signals presented to each ear simultaneously (using headphones). For example, in one experimental setup, three pairs of different digits were presented simultaneously, three digits in one ear and three in the other. Most participants in the study recalled the digits ear by ear, rather than pair by pair. Thus, if 496 were presented to one ear and 852 to the other, the recall would be 496-852 rather than 48-95-62.

In a selective attention experiment, the participant may be asked to repeat aloud the content of the attended message, a task known as shadowing. As Colin Cherry (1953) found, people recall 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 store. Performance on the unattended message is, of course, much worse. Participants are generally able to report almost nothing about the content of the unattended message. In fact, a change from English to German in the unattended channel usually goes unnoticed. However, participants are able to report that the unattended message is speech rather than non-verbal content.

Source separation problems in digital signal processing are those in which several signals have been mixed together and the objective is to find out what the original signals were. The classical example is the "cocktail party problem", where a number of people are talking simultaneously in a room (like at a cocktail party), and one is trying to follow one of the discussions. The human brain can handle this sort of auditory source separation problem, but it is a very tricky problem in digital signal processing. Although people can easily identify a particular sound source or particular person speaking in a live situation, when presented with recorded sound such distinctions between speakers become much less clear.

Live sound includes numerous variables that permit and promote selective attention, thus allowing people to easily differentiate the various sounds and their sources. This is not possible with recorded sound, where 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.

This phenomenon is still very much a subject of research, in humans as well as in computer implementations (where it is typically referred to as source separation or blind source separation). The neural mechanism in human brains is not yet fully clear.

Legacy

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.

Major Works

• Cherry, Colin E. "Some experiments on the recognition of speech with one and two ears." Journal of the Acoustical Society of America 25(5) (1953): 975-979. Retrieved October 4, 2011.
• Cherry, Colin E. On Human Communication: A Review, a Survey, and a Criticism. Cambridge, MA: The MIT Press, 1980 (original 1957). ISBN 978-0262530385
• Cherry, Colin E. World Communication: Threat or Promise. John Wiley & Sons Ltd, 1978 (original 1971). ISBN 978-0471996163
• Cherry, Colin E. The Age of Access: Information Technology and Social Revolution. Routledge Kegan & Paul, 1985. ISBN 978-0709934585 (edited and completed by William Edmondson)

References

ISBN links support NWE through referral fees

• Altman, Rick (ed.). Sound Theory, Sound Practice. New York, NY: Routledge, 1992. ISBN 978-0415904575
• Dean, Jeremy. The Cocktail Party Effect Psyblog (March 12, 2009). Retrieved October 4, 2011.
• Kantowitz, Barry H., and Robert D. Sorkin. Human Factors: Understanding People-System Relationships. New York, NY: Wiley, 1983. ISBN 978-0471095941
• O'Connor, J.J., and E.F. Robertson. Edward Colin Cherry, School of Mathematics and Statistics, University of St Andrews, Scotland, July 2008. Retrieved October 27, 2011.
• Wilder, Carol. A Conversation with Colin Cherry, Imperial College London, July 1976. Human Communication Research 3(4) (June 1977): 354–362. Retrieved October 27, 2011.

External links

All links retrieved October 29, 2011.

• List of the papers and correspondence of Colin Cherry 1914 - 1979
• Edward Colin Cherry University of St Andrews
• Colin Cherry Imperial College London
• E. Collin Cherry The Marconi Society

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