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Kharin
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In heaven all the interesting people are missing.
  
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Science finds key to music
« on: 2003-08-07 05:20:53 » |
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By Richard Black
BBC science correspondent
http://news.bbc.co.uk/1/hi/sci/tech/3129145.stm
Scientists in the United States believe they have solved one of the oldest puzzles in psychology - why does music take the form it does?
Writing in the Journal of Neuroscience, they say musical structure - chords and scales - is connected with patterns found in human speech.
The chord is the traditional building block of music from Haydn to Hendrix.
Chords and melodies can be broken down into their smallest parts, producing a scale of 12 notes - the chromatic scale.
It is not just a western phenomenon. Many musical traditions - some experts would say most - use the same 12-note scale.
"You have many musical cultures that don't have a 12-note scale, they may have five notes, a pentatonic scale, and yet we could not find any that had notes that were not in the chromatic scale or very close to it," David Schwartz of the Duke University in North Carolina told BBC News Online.
He said: "Not all these other cultures had all the notes we have, but there didn't seem to be any that have notes that we don't have."
But the researchers wondered why music was divided into 12 notes - why not 14, or 20, or three?
Speech-dominated environment
According to Dr Schwartz and his colleagues, it is because we are trained to by the sounds of speech.
The human speaking voice produces certain combinations of frequencies - pitches - and we look for those same combinations in music.
He said: "Speech is special because it is the sound that we are most often exposed to...
"We are immersed in it, we are bathed in it, we live in an acoustic environment dominated by speech and therefore speech sounds are going to play a major role in shaping the evolution and development of the auditory system."
One of the most pleasing musical chords is known as a major third and we find it familiar and pleasant, according to the new theory, because sub-consciously we hear the same combination daily in speech.
He said: "The reason why our perception seems to correspond so nicely with the statistical structure of speech sounds is that the brain... has in some way internalised the statistical structure of the sound environment we inhabit...
"There is this nice match between mind and world," said Dr Schwartz.
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the.bricoleur
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making sense of change
 
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Re:Science finds key to music
« Reply #1 on: 2003-08-07 07:04:42 » |
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Solving the mystery of musical harmony
Insights from a study of speech
DATE: 5-Aug-03
SOURCE:EurekAlert
DURHAM, N.C. -- For over two thousand years, musicians and scientists have puzzled over why some combinations of musical tones played together sound more harmonious than others. Now, Duke University perception scientists David Schwartz, Catherine Howe and Dale Purves have presented evidence that variation in the relative harmoniousness, or "consonance," of different tone combinations arises from people's exposure to the acoustical characteristics of speech sounds. Schwartz and Howe are postdoctoral fellows, and Purves is Director of the Center for Cognitive Neuroscience and the George B. Geller Professor of Neurobiology.
The researchers said that their findings, reported in the Aug. 6, 2003, issue of the Journal of Neuroscience, constitute an important advance in understanding the biological basis of music perception. The work also extends to hearing the theoretical framework about brain organization that Purves and his colleagues developed in earlier work on visual perception.
Those studies of vision led to the idea that evolution -- as well as individual experience during development -- created a visual system in which perceptions are determined by what a given visual stimulus has typically signified in the past, rather than simply representing to an observer what is presently 'out there.' That work is summarized in a new book entitled Why We See What We Do (Sinauer Associates, 2003).
In their Journal of Neuroscience paper, the neurobiologists present a statistical analysis of the patterns of frequency and amplitude in human speech sounds, based on a collection of recorded utterances spoken by more than 500 people. They found that the points at which sound energy is concentrated in the speech spectrum predict the chromatic scale -- the scale represented by the keys on a piano keyboard. Moreover, the difference in the amount of sound energy concentrated at these points predicts the relative consonance of different chromatic scale tone combinations.
These results suggest that certain pairs of tones sound more harmonious than others because they are physically similar to the patterns of sound energy most familiar to human listeners from their exposure to speech, said the researchers.
In deciding to analyze speech as a natural basis for tone perception, the researchers were faced with a very different challenge from that of exploring visual perception. In the work on vision, Purves and his colleagues concentrated on analyzing the perception of visual illusions.
"After studying the research literature on psychoacoustics, we discovered several phenomena in tone perception that, despite having been investigated for decades, remained unexplained," said Schwartz. "Our general framework is that the way to understand why somebody perceives anything the way they do -- whether the stimulus is light or sound-- is to consider the possible real world events that could have given rise to that particular stimulus.
"This work on music perception represents a natural extension of the work on visual perception," said Howe. "Hearing presents many of the same challenges as vision, in that the physical world cannot be known directly; we only know about objects in the environment because of the energy associated with them, such as light waves or sound waves.
"Determining the actual state of the environment on the basis of this indirect information available to our senses is a real challenge. The solution we have evolved is evidently to respond to ambiguous optical and acoustical stimuli by taking account of the statistical relationship between stimuli and their sources. That seems to be the reason we hear music the way we do."
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Durazac15
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Take me with water and a grain of salt
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Re:Science finds key to music
« Reply #3 on: 2004-04-07 15:46:37 » |
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Way to go Timebender:
Not in response to - but in addition to what Timebender said:
1> The Arabic world across the board uses quarter tones - which means there are way more than 12 notes in a scale. Some East Asian languages rely upon quarter tones as well. The chromatic scale is simple - not complex. Though I trust the scientists in the study in general, their view seems very westernized. This statement:
Quote:"You have many musical cultures that don't have a 12-note scale, they may have five notes, a pentatonic scale, and yet we could not find any that had notes that were not in the chromatic scale or very close to it," David Schwartz of the Duke University in North Carolina told BBC News Online.
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is completely meaningless - like saying no one uses colors we dont know about. Quarter tones are in no way like the chromatic scale. But sure they are close - it's not like there are other ways of transmitting sound. The frequencies must be in the human response range - and humans naturally divide things by .5, then .25 etc...
Also
Quote:These results suggest that certain pairs of tones sound more harmonious than others because they are physically similar to the patterns of sound energy most familiar to human listeners from their exposure to speech, said the researchers.
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This is unlikely IMO as well and is described at the end of #3.
2> The auditory canal and Pinna ( the shaped part of your ear ) have evolved along with the human voice to amplify sound in the 500 to 2000Hz to 3000Hz range. That means that by the time the sound reaches the ear drum, this range, which is the human vocal range, has significantly amplified that part of the sound spectrum - making it easier to understand human speech.
3> The auditory capabilities of humans, in theory, are between 20Hz and 20kHz. Yet the way we hear sound matches the physics perfectly. This is complicated to explain in a paragraph - but I'll try. The 20Hz to 20kHz is divided into 10 octaves (not be cause we selected 10 - but because the math dictated 10). The brain gives different weight to each octave. That is, if you had a device that made noise at the same level at all frequencies, the 31Hz octave band would be at about -15dB (deciBels), the 62Hz octave range this would be down about -10dB, at the 125Hz range, there is even less loss. This continues until about 4000Hz, where it strarts to drop off again. The Octaves are as follows:
31.5, 63, 125, 250, 500, 1000, 2000, 4000, 8000 and 16000Hz.
Notice anything about this progression? This will help - each of these numbers is the CENTER frequency for that octave. That is right, it is a logrythmic progression and each octave contains 2x as many frequencies as the previous octave.
The implication is that for frequencies between say, 20 and 48Hz (28 different frequencies), the brain thinks of the exact same way as it sees the 8000 frequencies in the 16k band.
If one were to make a sine wave of any pure tone, the brain would see them without preference for one tone or another. However, as soon as more than a single frequency is used, as in noise or music, harmonics, phase cancellation, and a million other effects come into play. The reason we like the 3rd tone cords, or the 5ths, or the 4ths (like here comes the bride) is because the harmonics created by these combinations are simple (they fall evenly in the spectrum), and there are not very many of them. Wheras if you were to take an out of tune instrument and do the same thing, though it might sound nice as a passing chord in jazz music, the combination creates a much more complex (objectivly speaking) or conflicting tones(aesthetically speaking) in which the resulting harmonics do not fall evenly in the scale.
Since I cannot write a book on it here and I am probably causeing more confusion - I'll stop here. So suffice it to say that what sounds good also works out nicely from a mathematical perspective. We never selected our notions of musical notes and scales - we evolved them.
4> Since this group assumes evolution is the engine of design - I think it is safe to assume that our hearing range is suited to speech because we need it as a survival trait. I also think it's safe to assume that if we needed to hear higher frequencies as a survival trait - we would have the ability. As for the lower frequency stuff - since anything between 5Hz and 15Hz is hazardous to our health at high level, and generally not produced by any animal other than perhaps Whales, there is no means of hearing these sounds. Though if you can feel a part of your insides vibrating - you are being exposed to dangerous levels of low freq - leave the location you are at.
Some may suggest - well what if we used different frequencies - like real high frequencies - wouldn't our ears have evolved for high freq speech? NO - you see there are many limitations upon sound at the high frequencies including:
1> The size of the organs necessary to convert the sound into something the brain can use
2> The energy required to transmit the sound over distance
3> The effects of air temp and density on sound waves
4> the need to hear the rest of the world - leaves rustling, footfalls, the lions roar, etc...
Although I am sure that on Planet X, where Hydrogen is the gas of choice for respiration, the animals did evolve with high freq hearing.
5> I'm not saying the Neuroscientists are wrong - just that they are looking at the issue from a different perspective. One perhaps not best suited to an understanding of accoustics. IMO their mistake is in the conversion of sound as physics as opposed to the subjective "feeling" of sound, better handled by people skilled in psychoacoustics, or bioacoustics.
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