Read the following text and draw a diagram of its structure.
VISUAL AND AUDITORY SPACE
The amount of information gathered by the eyes as contrasted with the ears has not been precisely calculated. Such a calculation not only involves a translation process, but scientists have been handicapped by lack of knowledge of what to count. A general notion, however, of the relative complexities of the two systems can be obtained by comparing the size of the nerves connecting the eyes and the ears to the centres of the brain. Since the optic nerve contains roughly eighteen times as many neurons as the cochlear nerve, we assume it transmits at least that much more information. Actually, in normally alert subjects, it is probable that the eyes may be as much as a thousand times as effective as the ears in sweeping up information.
The area that the unaided ear can effectively cover in the course of daily living is quite limited. Up to twenty feet the ear is very efficient. At about one hundred feet, one-way vocal communication is possible, at somewhat slower rate than at conversational distances, while two-way conversation is very considerably altered. Beyond this distance, the auditory cues with which man works begin to break down rapidly. The unaided eye, on the other hand, sweeps up an extraordinary amount of information within a hundred-yard radius and is still quite efficient for human interaction at a mile.
The impulses that activate the ear and the eye differ in speed as well as in quality. At temperatures of 0°C. (32°F.) at sea level, sound waves travel 1100 feet a second and can be heard at frequencies of 50 to 15,000 cycles per second. Light rays travel 186,000 miles a second and are visible at frequencies of 10,000,000,000,000,000 cycles per second.
The type and complexity of the instruments used to extend the eye and the ear indicate the amount of information handled by the two systems. Radio is much simpler to build and was developed long before television. Even today, with our refined techniques for extending man's senses, there is a great difference in the quality of the reproductions of sound and vision. It is possible to produce a level of audio fidelity that exceeds the ability of the ear to detect distortion, whereas the visual image is little more than a moving reminder system that has to be translated before it can be interpreted by the brain.
Not only is there a great difference in the amount and type of information that the two receptor systems can process, but also in the amount of space that can be probed effectively by these two systems. A sound barrier at a distance of a quarter of a mile is hardly detectable. This would not be true of a high wall or screen that shuts out a view. Visual space, therefore, has an entirely different character than auditory space. Visual information tends to be less ambiguous and more focused than auditory information. A major exception is the hearing of a blind person who learns to selectively attend the higher audio frequencies which enable him to locate objects in a room.
Bats, of course, live in a world of focused sound which they produce like radar, enabling them to locate objects as small as a mosquito. Dolphins, too, use very high-frequency sound rather than sight to navigate and locate food. It should be noted that sound travels four times as fast in water as it does in air.
What is not known technically is the effect of incongruity between visual and auditory space. Are sighted people more likely to stumble over chairs in reverberating rooms, for example? Is it easier to listen to someone else if his voice is coming from one readily located spot instead of from several loudspeakers as is characteristic of our P.A. systems? There is some data, however, on auditory space as a factor in performance. A study by J. W. Black, a phonetician, demonstrated that the size and reverberation time of a room affects reading rates. People read more slowly in larger rooms where the reverberation time is slower than they do in smaller rooms. One of my own interview subjects, a gifted English architect, perspicaciously improved the performance of a malfunctioning committee by bringing in line the auditory and visual worlds of the conference chamber. There had been so many complaints about the inadequacy of the chairman that a replacement was about to be requested. The architect had reason to believe that there was more in the environment than in the chairman to explain the difficulties. Without telling his subjects what he was doing, the architect managed to retain the chairman while he corrected environmental faults. The meeting room was next to a busy street whose traffic noises were intensified by reverberations from the hard walls and rugless floors inside. When reduction of the auditory interference made it possible to conduct a meeting without undue strain, complaints about the chairman ceased.
It should be noted here by way of explanation that the capacity of the "public school" upper-class English to direct and modulate the voice is far greater than that of Americans. The annoyance the English experience when acoustic interference makes it difficult to direct the voice is very great indeed. One sees the sensitivity of the English to acoustic space in Sir Basil Spence's successful recreation of the atmosphere of the original Coventry cathedral (destroyed during the war) while using a new and visually daring design. Sir Basil felt that a cathedral should not only look like a cathedral but should sound like one as well. Choosing the cathedral at Durham as a model, he tested literally hundreds of samples of plaster until he found one that had all the desired acoustic qualities.
Space perception is not only a matter of what can be perceived but what can be screened out. People brought up in different cultures learn as children, without ever knowing that they have done so, to screen out one type of information while paying close attention to another. Once set, these perceptual patterns apparently remain quite stable throughout life. The Japanese, for example, screen visually in a variety of ways but are perfectly content with paper walls as acoustic screens. Spending the night at a Japanese inn while a party is going on next door is a new sensory experience for the Westerner. In contrast, the Germans and the Dutch depend on thick walls and double doors to screen sound, and have difficulty if they must rely on their own powers of concentration to screen out sound. If two rooms are the same size and one screens out sound but the other one doesn't, the sensitive German who is trying to concentrate will feel less crowded in the former because he feels less intruded on.