Unlocking the Musical Mysteries of the Human Cochlea
Introduction
The human ear is a marvel of biological engineering, capable of not only perceiving sound but also, it seems, resonating with the fundamental principles of music itself. In a groundbreaking study led by Dr. K.J. Blinowska and colleagues, published in PLoS ONE, researchers delve deep into the cochlea, the auditory portion of the inner ear, uncovering a surprising connection between its workings and the mathematical beauty of musical ratios.
Investigating Cochlear Resonance
The study involved a meticulous process where researchers pooled frequencies from the cochlea and analyzed their ratios. They repeated this procedure 1000 times to construct 1000 distributions of random ratios. This enabled them to discern a mean random distribution, against which they could compare their experimental data.
The Significance Unveiled
By subtracting the random background from the distribution obtained from individual ears, the researchers identified significant peaks that deviated from the random distribution. Remarkably, they found 10 clearly defined peaks, closely resembling small-integer ratios typical of Just intervals in the diatonic scale:
9:8 - Major second
6:5 - Minor third
5:4 - Major third
4:3 - Perfect fourth
7:5 - Lesser septimal tritone
3:2 - Perfect fifth
8:5 - Minor sixth
5:3 - Major sixth
Time–frequency representation of TEOAEs for the left and right ears of one subject:
Validation Through Statistical Weight
Previous studies had hinted at the presence of musical intervals in otoacoustic emissions (OAEs), but lacked statistical robustness. Unlike these earlier findings, the current study employed an improved methodology, yielding results with stronger statistical justification. Moreover, the study's findings align with experimental evidence from diverse sources, further validating its conclusions.
Implications and Interpretations
The discovery of almost all main intervals from the Just scale within the cochlea raises profound questions about the nature of music perception. Traditionally believed to reside in cortical processing, the perception of musical intervals may, in fact, have roots in subcortical structures like the brainstem, as suggested by recent research.
The Pythagorean Connection
The study evokes the ancient insights of Pythagoras, who linked musical harmony with mathematical ratios. Indeed, the presence of perfect fifths and fourths, ubiquitous in various musical traditions, resonates not only in compositions but also in the very anatomy of our auditory system.
Conclusion
The intricate workings of the human ear continue to astound and inspire. Through a fusion of meticulous experimentation and theoretical insight, this study led by Dr. K.J. Blinowska and colleagues unveils a remarkable harmony between the cochlea and the musical scale. As we unravel the mysteries of our auditory system, we come one step closer to understanding the profound connection between music and the human experience.
Note from Rudi Wienand
This is also one more evidence for the soothing and relaxing effect that just intonation scales have on us. Overtones, like in overtone rich instruments such as the Indian Sitar or in mongolian and tibetan throat singing appear naturally in these same intervals. Also the soundscapes I compose and produce are all resonating with these simple and natural intervals.
The cochlea itself, the very organ that perceives soundwaves and transforms these into electric signals that are sent to the auditory cortex in the brain via the auditory nerve, resonates biologically, organically, and naturally with these simple ratios. Like the planetary orbital movements that also relate to each other in the same ratios. What is inside, is outside and vice versa. We are a biological reflection from one another, the macrocosmos and the microcosmos resounding in intimate harmony.
So to say, if I perceive these natural harmonic ratios as musical intervals, it is much easier for the cochlea to process them as they resound with the cochlea's own biological configuration. When we perceive well tempered scales, where the intervals are slightly moved form their natural ratio, the cochlea itself has a harder time processing the information. Almost all modern music available to our ears is tuned to the so called well tempered scale, unnecessarily stressing our inner ear and nervous system
References
1. Zatorre RJ, Peretz I (2001) The Biological Foundations of Music. Ann N Y Acad Sci 930.
2. Blinowska KJ, Jedrzejczak WW, Konopka W (2005) Resonant modes and musical ratios in otoacoustic emissions. Biol Cybern 93: 366–377.
3. Lee K, Skoe E, Kraus N, Ashley R (2009) Selective subcortical enhancement of musical intervals in musicians. J Neurosci 29: 5832–5840.
4. Bidelman G, Krishnan A (2009) Neural correlates of consonance, dissonance, and the hierarchy of musical pitch in the human brainstem. J Neurosci 29: 13165–13171.
5. Bell A, Fletcher NH (2004) The cochlear amplifier as a standing wave: Squirting waves between rows of outer hair cells? J Acoust Soc Am 116: 1016–1024.
