Alex Storer
whose TA is Rob
humbly submits this essay
regarding
MUSICAL COGNITION
for
MCB 61
on
April 29, 2002
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As an intended music minor and an avid (yet rather inadequate) musician, it has
become more and more obvious to me that the science of music is virtually ignored.
Clearly, for such a universal standard to be in place regarding the precision and accuracy
of certain musical concepts, a biological basis must underlie the artistry of music. In this
paper, I will explore the neurological underpinnings of music and how they form a cogent
system of building blocks that leads to the complexities seen in modern compositions.
While the perception of music is a high level process and very difficult to comprehend as
a cogent whole, each facet of musical perception can be at least partially deconstructed
into neurological function, each of which is actually processed at a most basic level aside
from the other aspects of the music.
The essential elements of music can be isolated to several qualities that the human
brain perceives. Perhaps the most simplistic of these is loudness, a measurement of the
volume of a particular sound. Loudness is essential in music; changing the volume at
specific times can change the mood of and meaning behind a piece. Louder sounds cause
greater vibration in the basilar membrane, which is located in the cochlea.
These
vibrations cause the axons to fire more rapidly, which is in turn translated as a louder
sound in the auditory pathways of the brain (Kolb, 2001). While little is known about the
processing of loudness in the brain, studies have shown differences between musicians
and non-musicians, implying that training can influence this part of musical perception.
Specifically, musicians are able to maintain perception of loudness longer than nonmusicians, who will adapt to the loudness and perceive it as decreased over time
(Chrystophe, 1995). This process is important for musicians to have a more accurate
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assessment of their music as it is being played, and it’s understandable that this ability
would be more fine-tuned for musicians.
Rhythm is another important part of all types of music, and to understand the
perception of music as a whole it is necessary to understand how these are processed.
From a logical standpoint, rhythm involves mechanisms for timing, motor coordination
and additional auditory processing. The cerebellum, basal ganglia and superior temporal
gyrus provide the mechanisms necessary for analyzing duration of tones as well as motor
timing necessary to create rhythmic sequences (Dennis, 2001). Rhythms, however, are
not confined to only one part of the brain (Dennis, 2001). After losing full functionality
in either hemisphere, patients’ abilities to detect and reproduce rhythms falter. Rhythm,
rather than duration, however, is more of a high level process that cannot be quite so
simply stated. In addition to the mere function of duration, how long a beat lasts, music
implies the concept of meter, the organization of beats into logical groups. For example,
quadruple meter implies that there are four beats of equal length in one measure, or
grouping of notes. This system involves collaboration between temporal lobes.
Perhaps the most well known element of music is pitch, the quality of a tone.
From a physical standpoint, pitch is defined by the frequency of a sound wave. In music,
relative pitch is used to compare notes in the scale and defines the building blocks of
tonal progressions. These are defined in terms of ratios of the frequencies of pitches. A
perfect fifth, such as from C to G, has a ratio of 3:2. Similarly, other relationships have
frequency ratios in terms of relatively simple fractions (WWW 1). While the basic
hearing of pitch takes place in the primary auditory cortex, the analysis of these
frequencies takes place away from this, mostly in the temporal lobes.
The most
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noteworthy studies regarding musical perception lie in hemispherical analysis, perhaps
because it is easiest to observe. The ability to experience melody seems to be focused on
the right hemisphere of the brain, as is documented by Dennis & Hopyan. In fact,
injections to temporarily disable right brain function show marked loss of melodic
abilities without affecting rhythm or language (2001).
Another fascinating attribute of pitch is the notion of absolute pitch.
Most
humans are not able to identify a given pitch by name, but the ability to do so is found in
approximately 1 in 10,000 people. On a neurological level, absolute pitch is associated in
some way with the planum temporale, and hemispherical asymmetries therein.
Surprisingly enough, leftward asymmetries are common in musicians with absolute pitch.
Normally, this would not seem reasonable due to the large number of musical functions
associated with the right hemisphere of the brain (Keenan, 2001). This asymmetry is
postulated to be a result of genetics, as the lateralization of the planum temporale can be
seen even in utero. Another central cause of absolute pitch is musical training between
the ages of 3 and 6, which attests to the mutability of the brain at young ages. It also
spawns my general distaste towards my parents and their inability to provide me with
suitable music lessons at an exorbitantly young age.
While each one of these elements of music can be analyzed, it’s difficult to find
material regarding how the brain pieces this information together to create a musical
sensation. Instead, there are multiple approaches from the top down to approach music,
focusing on theory and psychological or physiological effects of listening to it. It is
postulated, however, that human ability to perceive music as a whole came with the
development of a more extensive dopaminurgic system (Previc, 1999).
Additional
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complexities of musical perception are covered in the emerging field of
neuromusicology, which plans to turn musical theory into neurological theory. Despite
the lack of strong research at this point, it holds great promise for the future of
neurological musical analysis.
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References
Christophe, M. Medial Olivocochlear System and Loudness Adaptation: Differences
between Musicans and Non-musicians. Brain and Cognition 29: 127-136 (1995)
Dennis, M. et al. Rhythm and Melody in Children and Adolescents after Left or Right
Temporal Lobectomy. Brain and Cognition 47: 461-469 (2001).
Keenan, J.P. et al. Absolute Pitch and Planum Temporale. NeuroImage 14: 1402–1408
(2001)
Kolb, B. et al. An Introduction to Brain and Behavior. Worth Publishers (2001).
Previc, H. P. Dopamine and the Origins of Human Intelligence. Brain and Cognition 41:
299-350 (1999)
WWW 1. The Mathematics of Tuning and Temperament.
<http://www.hlalapansi.demon.co.uk/Acoustics/MusicMaths/MusicMaths.html>