Of all the forms of human aesthetic expression on this planet, none has been so carefully studied than the "temporal art" of music. Music, the "language of emotion," has been the object of intense speculation among philosophers for many millennia. (See Merriam,1744 Révész,701 and Seashore.700) For modern xenologists, perhaps the most central question is: Why do people listen to music? If some rational basis can be identified for humans, the same analysis may be generalizable to our consideration of xenoaesthetic response.
Why do we listen? Ethologists have suggested that human beings may have certain inborn releasing mechanisms that automatically respond to rhythm, percussion and melody.2902 There is no question that the perception of musical sound causes distinct physiological reactions involving nervous control, blood circulation, digestion, metabolism, body temperature, hunger and thirst, sex drive, posture and balance.700 Sociobiologists point out that various forms of music are produced by animals throughout the world, including the songs of birds and the carnival displays of primates.565 But musicologists insist that we listen to music both because it gives us pleasure and because music is a system of symbolic communication660 which stimulates emotional, frequently visual, imagery. (See Crossley-Holland,669 Merriam,1744 and Swanwick.666) One researcher "had visions of locomotives thundering by" when dozing during a Brahms rhapsody, and described the reaction of one of his students to a string quartet composed by Ruth Crawford for a class in music appreciation as follows: "It produced a vision of a fly struggling in a spider web while the spider prepared to devour it."663
Probably the view among musicologists that "music transforms experience"662 is not far from the truth. Ethnomusicologists -- scientists who study the anthropology of music -- agree that the effects of the artform are very strongly culture-bound.1744 Western music, for instance, is not recognized as expressing emotion by many "primitive" African tribes, and is often described as a "dull monotone" by Chinese. But to Westerners thoroughly steeped in classical European tradition, Chinese music and the music of the Middle East often sounds like an aimless cacophony of noise devoid of emotional meaning. Like the expression of emotion itself, the appreciation of specific musical forms has major cognitive and culturally-determined elements.*1744,697
Why, then, do we listen to music? Undoubtedly the real answer lies in the negentropic character of all lifeforms.3071 Since it is lifeís business to accumulate information and complexity, organisms have an inherent predisposition to pursue and to absorb negentropic order whenever and wherever possible. Music and other art forms are perceived by humans as a layer of complexity and structure imposed upon an otherwise chaotic sensory environment, since art is known to have a major informational component. (See Chamberlain,664 Heyduk,667 and Pierce.1742) One theorist even gives a simple method for calculating the number of "bits" of information contained in a musical score.1815
Leonard B. Meyer has suggested that the best music has a great deal of information designed into it by the composer. He calls this "designed uncertainty." Meyer continues:
As a musical event unfolds and the probability of a particular conclusion increases, uncertainty, information, and meaning will necessarily decrease. Systemic uncertainty of necessity exists at the beginning of a piece of music where the relationships between tones are being established. If music operated only with systemic uncertainty, meaning and information would necessarily decrease. But music is able to combat the tendency toward the tedium of maximum certainty through the designed uncertainty introduced by the composer. On the basis of this analysis we should expect designed deviations, delays, and ambiguities to be introduced as systemic probability increases -- as the pattern approaches completion. This expectation is borne out by the practice of musicians.1774
So we listen to music because it satisfies a kind of mental "negentropic hunger," a hunger we may share with all emotional extraterrestrial lifeforms anywhere in the universe. But there are many, many different patterns of sound capable of conveying information and structural complexity in tone and rhythm.3699 Indeed, a simply melody consisting of 100 notes, each chosen from a field of ten, may assume 10100 different forms. Why do humans prefer just a few of these?
Dr. Richard F.Voss, a young physicist at the Thomas J. Watson Research Center of IBM, has found at least a partial answer to this most difficult question.2881 In a seminal paper, published earlier in 1978 in the Journal of the Acoustical Society of America, Voss identifies the central characteristic common to all forms of human musical experience.3017 (A similar analysis theoretically may be performed on other modes of aesthetic expres sion, though such has not yet been attempted.) Vossí technique demonstrates that manís perception of emotionally satisfying artistic forms is directly related to the organization of the human brain.
Dr. Voss' theory is based on the technical concept of "autocorrelation." The autocorrelation of a sequence of musical notes is the measure of how closely the present fluctuations of the signal are related to past fluctuations. A steady tone, for instance, is fully autocorrelated, since the present sound can be predicted with absolute certainty from a knowledge of previous sound (i.e., it will stay the same). A completely non-autocorrelated signal does not depend at all upon prior states. Each musical note is chosen entirely independently of all others in the sequence. Information theorists call this kind of signal "white noise." White noise occurs most commonly in nature as the thermal noise produced by random motions of electrons through an electrical resistance. This causes static in radio and "snow" on television screens. Musical compositions can be created by mimicking this random process of selection, say, by tossing dice to determine the next note. Voss calls these works "white music."
A very highly correlated form of noise, called "Brownian noise," takes its name from the physical phenomenon of Brownian motion. This may be observed under the microscope -- the random movements of small particles or organisms suspended in liquid water and buffeted by the thermal agitation of molecules much like bumper cars at carnivals. Each particle executes a three-dimensional random walk, the sequential positions of which describe a highly correlated sequence. The particle "remembers" where it has been. Voss calls melodies constructed in the pattern of Brownian noise "brown music." Rather than choose the next note in the sequence at random, brown music is generated by throwing dice to determine how many notes to progress up or down the musical scale from the present position. Velocity, not position, is selected randomly.
Brown music is highly autocorrelated; white music is very non-autocorrelated. Vossí insight was to examine a class of noise having an intermediate level of autocorrelation. In electronics it has a special name: Flicker noise, or "1/f noise." Voss generated several musical compositions according to the white, brown, and flicker patterns. Invariably, test subjects preferred "flicker music" (Figure 22.1) to either white music or brown music. But the reason for this preference remained unclear.
Figure 22.1 Voss' Theory of Flicker Music2861
Then surprising new information began to emerge. 1/f noise was found to be extremely commonplace in nature. For example, the record of the annual flood levels of the Nile follows a 1/f fluctuation. Variations in sunspots, the wobbling of Earthís axis, undersea currents, membrane currents in the nervous systems of animals, errors of measurement in atomic clocks, and traffic flows on expressways all exhibit a recognizable flicker pattern.
T. Musha, a physicist at the Tokyo Institute of Technology, rotated a radar beam from a coastal location to get a maximum variation of landscape on the radar screen. The pattern was Brownian. However, when he rotated the beam twice and subtracted one image from the other (representing all the changes in the scene between the two sweeps) the resulting pattern was distinctly 1/f. The static world is very Brownian, in other words, but the dynamic world appears 1/f.
It is Vossí contention that the human brain also may best be character ized by flicker rather than Brownian or white patterns. Human brains prefer compositions of sound with only moderate autocorrelation, and this is how we choose the music we like. Explains one writer:
We are now approaching an understanding of Vossí daring conjecture. The changing landscape of the world (or to put it another way the changing content of our total experience) seems to cluster around 1/f noise. It is certainly not entirely uncorrelated, like white noise, nor is it as strongly correlated as brown noise. From the cradle to the grave our brain is processing the fluctuating data that come to it from its sensors. If we measure this noise at the peripheries of the nervous system (under the skin of the fingers), it tends to be white. The closer one gets to the brain, however, the closer the electrical fluctuations approach 1/f. The nervous system seems to act like a complex filtering device, screening out irrelevant elements and processing only the patterns of change that are useful for intelligent behavior.2881
We like flicker music best because it parallels the way our brain works. Our mental "negentropic hunger" demands a sensory diet of "1/f food." And since 1/f is the pattern of dynamic reality, we may expect that the neural equipment of many alien sentients will be organized in much the same way.
There are also a number of. physiological sensory limitations upon the music that extraterrestrials may enjoy. First there is the question of frequency response of alien ears. The average human can hear from 20-20,000 Hz. He can discriminate 600 distinct pitches at whisper loudness (5 dB) and 1800 pitches at the loudness of normal speech (about 60 dB).696 In spite of this, Western music makes use of no more than 100 distinct pitches, and even if other cultures are added in the total does not approach the theoretical maxima. Our music is comparatively poor.
The human ear has a hearing range of about 10 octaves, a music range of 8 octaves, a normal performing range of about 5 octaves, and a talking range of less than 1 octave. To the dolphin, with hearing from 100-200,000 Hz (11 octaves) and normal "speech" from perhaps 4000-40,000 Hz (3 octaves), our normal speech must sound incredibly dull, flat, and monotone. The entire human music range spans only the five bottommost octaves of dolphin hearing, and our normal performing range spans less than four. ETs with hearing ranges or pitch discrimination markedly different from humans may be unable to appreciate our speciesí music, and vice versa.
Fortunately, however, evidence marshalled by xenologists indicates the differences may not be too great in many cases. Most land animals on Earth, including amphibians, birds and mammals, have maximum hearing limits between 10,000-100,000 Hz. While there are a number of notable exceptions (such as the alligator and the dolphin), aliens who evolutionarily have committed themselves to hearing as a major sensory modality probably will not fall much outside this range.
The lower limit of hearing is fixed by even more fundamental considerations. The relative insensitivity of the human ear at low frequencies protects us from the distractions of normal bodily vibrations.82 If we could hear below 10 Hz, our ears constantly would be bombarded with the creaks and groans of jointed skeletons, trapped gases and flexing musculature. There may exist ETs with uniformly soft mushy bodies that do not squeak, groan, or burble. But if they have any hard parts at all, chances are that aliens wonít hear below about 10 Hz either.
There is also the question of rhythm in music.696 The basic unit of musical time is called a beat. The pace of the fundamental beat is called the tempo. What are the upper and lower limits of tempo in alien music?
As for the upper limit, human nervous tissue imposes a maximum rate of transmission for discrete signals of about 3 milliseconds (18,000 beats/minute).454 This theoretical maximum for human beings cannot nearly be reached in practice, since musical messages must be processed through a complex network involving ear and brain structures. Generally, as with flickering light impinging the eye, musical sequences faster than about 20 notes per second (1200 beats/minute) lose their periodicity and become perceptually continuous phenomena. This is also the fastest speed at which notes may be separately fingered on a piano by human hands.665 It is certainly possible that extraterrestrials may have faster response times than this, but it is doubtful that it can be much faster if biological building materials are used. The human flicker response of 20 events/second is an evolutionary adaptation which promotes survival by permitting detection of fast-occurring survival-related events in the environment. ETs on high gravity worlds may have reflexes twice as fast as our own (giving them a flicker rate of 2400 beats/minute), but it is doubtful that still faster perception would serve any biologically useful purpose.
Ambient temperature has been shown to affect circadian rhythms and the flow of subjective time in animals and humans. Temperature and time are directly correlated: As temperature rises, subjective time seems to pass faster. In one memorable experiment, humans were required to tap a key at the subjective rate of three taps per second. When body temperature was artificially raised by diathermy, an acceleration in the tapping rhythm was observed of which the subjects were not aware.91 Biochemical reactions generally go faster at elevated temperatures, and neurochemistry is no exception. Given similar biochemistries, xenologists expect warm climate aliens generally to prefer faster musical tempos and have faster flicker rates than extraterrestrial beings indigenous to colder climes.
As for the lower limit of tempo, humans are known to have a neurologically-determined attention span of from 2-10 seconds (6-30 beats/minute).665,1815 Studies have shown that the perception of rhythm disappears when beats follow each other by more than 2 seconds.91 Attention span, like flicker rate, is determined by evolution. ETs native to low gravity, very cold worlds might have very long attention spans by human standards. Since nothing would happen very quickly on such a planet, lifeforms would need to be more patient to discern developing survival-related patterns in the sensory environment. The music of these creatures, perhaps involving a minimum tempo of 1 beat/minute, would prove well-nigh intolerable to human ears.
What about the preferred tempo? Human music normally runs at about 50-95 beats/minute, and a rather striking convergence on 70-80 beats/minute has been discovered among terrestrial cultures all over the world.91,698 Musicologists had long believed that the appreciation of specific tempos was probably a learned product of culture. But since many societies seem to choose the same "most pleasing" tempo, the explanation may lie in some characteristic of human physiology.
One fascinating theory goes as follows.661,698 For the first 9 months of its existence, the developing fetus is exposed to its motherís heartbeat (normally 80 beats/minute) and to the periodic swaying due to the normal walking stride of pregnant mothers (also about 70-80 beats/minute). Newborn babies continue to hear the motherís heartbeat when held to the chest for nursing or fondling. And experiments have shown that 70-80 beat/minute heartbeat sounds played over loudspeakers in hospital nurseries have an observable quieting effect on infants.661,82 So it may be that humans early learn to associate an aural environment of 70-80 beats/minute with warmth and security, imprinting this preferred tempo upon them for life. Later, the music they make naturally tends to cluster around 70-80 beats/minute.
The implications for xenology are clear. Aliens with different heartbeat timing may have different preference tempos in their music. ETs with markedly different maternal heartbeat and walk-strides may have two distinct preferred tempos around which their songs tend to cluster. Sentient species without heartbeats, without strides (e.g., no legs), or which hatch from eggs and so never experience the motherís heartbeat or stride, may have no preferred tempo whatsoever, or it may be fixed by other factors.
Of course, the temporal arts are not strictly limited to the perception of sound. Other beings may make music utilizing other sensory modalities. Creatures who rely primarily on vision for communication may play visual music with flickering lights of varying colors, intensities, and tempos. They would doubtless find our Lasariums rather primitive efforts; and could humans ever hope fully to appreciate the nuances of prismatic harmony?
The phrase "electronic music" takes on new meaning when applied to electrosensitive extraterrestrials, and one wonders what mankind could make of dynamic magnetic music. Olfactory aliens may devise smell-symphonies, performed in giant auditoriums constructed much like wind tunnels. Delicate aromas suggestive of moods or activities such as sex or physical combat could be combined to create emotional musical dramas. (The accidental "breaking of wind" by an embarrassed patron, the osmic equivalent of shouting scatological curses in a human theater, would surely be grounds for ejection by the ushers.)
* The political, economic, and social ideologies of cultures frequently are enshrined in their music and art.2363