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This post concludes the three-part survey of musical embodiment—the idea that music isn’t just a mental experience but one that involves our entire body, and how this physical connection shapes our musical preferences. Last month’s post featured the predictive coding model, which asserts that musical preferences are learned and therefore mainly cultural. Because this learning happens in the cortex, the advanced upper regions of the brain, it is called a “top-down” model.
We now turn to neural resonance theory, which proposes that our musical preferences are innate and deeply biological. This is a “bottom-up” model since much of the processing of the sound we hear begins early—in the inner ear and brainstem—along the auditory (hearing) pathway. (Note: this post explores melody; rhythm will be the focus of a future post.)
We Sync to Music
Consider this quote as the motto of neural resonance theory (NRT): “Your brain and body literally sync to music.”1
Musical notes, like all sounds, are created by vibrations of air molecules. When these vibration waves reach the cochlea (the sound detector organ of the inner ear), they activate it to fire signals in sync with the frequencies of the notes.
We measure sound frequencies in cycles per second, or Hertz (Hz), named for physicist Heinrich Hertz. The cochlea translates mechanical air molecule vibration into an electrochemical signal firing (called resonance) at matching frequencies.
For example, concert A, the note to which an orchestra tunes, is the A above middle C. It is labeled A4 and has a frequency of 440 Hz. The part of your cochlea that detects A4 converts its mechanical sound waves into electrochemical nerve signals that fire, or resonate, at the same frequency.2
This incredible ability to detect and convert frequencies allows our auditory system to tell notes apart. Without it, melody could not exist.
Exiting the cochlea, these electrochemical signals move along the auditory nerve to the brainstem. They then travel upward in the brainstem, pass through the thalamus, and reach the primary auditory region of the brain’s temporal lobes. The nerves along this entire pathway fire at frequencies that match the musical notes. Your nervous system is thus dynamic, physically resonating with the music in its environment.
The Math Behind the Sounds
Melody is a sequence of varying musical notes. Because nerve signals mirror sound frequencies, we can map the relationships between musical notes using mathematical ratios:
The ratio of a note to the note an octave above it is 2:1 (the frequency of A5 is 880 Hz). The ratio of a note to the fourth above it (A4 to D5) is 4:3 (the frequency of D5 is 586.67 Hz) and to the fifth above it (A4 to E5) is 3:2 (the frequency of E5 is 660 Hz). These and other simple ratios are typically experienced as pleasant or consonant.
Contrast this with the ratio of a major seventh (A4 to G♯5), 15:8, and of the tritone (A4 to D♯5), 45:32.3 These and other complex ratios are typically experienced as harsh or dissonant.
According to NRT, our brain innately favors smooth, simple ratios (consonance) and disfavors clashing, complex ratios (dissonance).4 This doesn’t mean it is always averse to dissonance—music that’s exclusively consonant is boring. Instead, our brain can enjoy the tension of dissonance provided it resolves back to consonance.
Thus, the brain anticipates resolution to consonance because of its innate biology, not because it has learned to do so. This explains why you can love the same song the hundredth time you hear it—your neural circuits continue to sync with its wonderful musical patterns (resonances) even though you know the song so well you make no more prediction errors about it.5
Edward Large, Ph.D., a Professor of Physics and of Psychological Sciences at the University of Connecticut, is a pioneer of NRT. He and his colleagues argue that we do not simply calculate what note comes next; rather, our brain-body dynamics physically mirror the structure of the music. Initially drawn to NRT due to its elegant mathematics, Dr. Large points out that these mathematical ratios are not abstract concepts—they are the real-time firing rates within your nervous system.6
Neuroscience Essential Reads
How Resonance Generates Emotions and Feelings
Both the predictive coding model (PCM) and NRT activate the limbic system to generate sentiments (emotions and feelings), but each does so in its own manner. In PCM, instructions based chiefly upon learned musical preferences are transmitted to the limbic system to prompt it to act. With NRT, the physical resonances of the nerve signals—arising from and corresponding to the notes of the musical source—rattle through pathways that trigger the limbic system.7
Once the limbic system is turned on, likes and dislikes are realized in NRT the same way as in PCM: by the release of nerve and chemical signals that generate embodied emotions and feelings.8 NRT is thus doubly embodied: the resonances that sync with the musical notes and the sentiments felt in the brain’s map of the body.
Evolutionary Advantage
How does innately recognizing melody, the resonance ratios of musical tones, benefit humans? Consider these two survival values. First, speed: as certain tonal combinations indicate natural danger, like a predator in the bush, a rapid reflex response enables your body to react and jump away before your conscious brain even registers what the sound is. Second, attention: the world is full of chaotic background noise, and melodies serve as clean auditory anchors, helping the brain filter out static and focus on what is important.
Wrap-Up
So, which approach is correct: predictive coding or neural resonance theory? Do our musical preferences come from cultural learning or biological hardwiring? The answer is likely a combination of both.
As renowned neurologist Norman Geschwind wrote, complex human behaviors require a genetic foundation to make the behavior possible, combined with real-world instruction and practice to bring it to life.9 And, in keeping with the theme of this three-part series, both approaches lean into the concept of embodiment, that music is a mutual experience of our brain and of our body.
