This post concludes a three-part survey of musical embodiment—the idea that music is not just a mental experience, but a whole-body experience, and how this physical connection shapes our musical preferences. Last month’s post There is a predictive coding model that posits that musical preferences are learned and therefore largely cultural. Because this learning takes place in the cortex of the higher parts 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 because much of the processing of the sound we hear begins early along the auditory (auditory) pathway—the inner ear and brainstem. (Note: this post explores melody; rhythm will be the focus of a future post.)
Synchronize with music
Consider this quote as the motto of Neural Resonance Theory (NRT): “Your brain and body are literally in sync with the music.”1
Musical notes, like all sounds, are created by the vibrations of air molecules. When these vibrational waves reach the cochlea (the sound-detecting 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 after the physicist Heinrich Hertz. The cochlea mechanically converts the vibration of the air molecule into an electrochemical signal burst (called resonance) at the corresponding frequencies.
For example, the note A concert played by an orchestra is an A above a 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 amazing ability to detect and convert frequencies allows our auditory system to distinguish between notes. Without it, the melody would not exist.
Leaving the cochlea, these electrochemical signals travel along the auditory nerve to the brainstem. They then travel up the brainstem, pass through the thalamus, and reach the main auditory region of the temporal lobes of the brain. Nerves along this pathway fire at frequencies that correspond to musical notes. Yours nervous system Thus, the speaker physically resonates with the music in its environment.
The math behind the sounds
A melody is a sequence of different musical notes. Since nerve signals reflect sound frequencies, we can map the relationship between musical notes using mathematical ratios:
The ratio of the note to the octave above it is 2:1 (A5 frequency 880 Hz). The ratio of the note to the fourth above it (A4 to D5) is 4:3 (D5 frequency 586.67 Hz) and to the fifth above it (A4 to E5) 3:2 (E5 frequency 660 Hz). These and other simple ratios are usually taken as pleasant or consonant.
Contrast this with the major seventh (A4 to G♯5), 15:8, and the tritone (A4 to D♯5), 45:32.3 These and other complex ratios are often seen as rigid or dissonant.
According to NRT, our brains innately prefer smooth, simple proportions (consonance) and reject conflicting, complex proportions (dissonance).4 This does not mean that he does not always like dissonance – only consonant music boring. Instead, if it returns to consonance, our brain can enjoy the tension of dissonance.
Thus, the brain expects coherence not because it has learned to learn, but because of its innate biology. This explains why you can love the same song the hundredth time you hear it – your neural circuits continue to synchronize with its wonderful musical patterns (resonances), even though you know the song so well that you don’t make any more prediction errors.5
Edward Large, PhD, professor of physics and psychology at the University of Connecticut, is a pioneer of NRT. He and his colleagues point out that we don’t just calculate the next note; rather, our brain-body dynamics physically reflect the structure of the music. Originally drawn to NRT because of its elegant mathematics, Dr. Large points out that these mathematical ratios are not abstract concepts—they are real-time firing rates in your nervous system.6
Neuroscience Essential Readings
How resonance creates emotions and feelings
Both the Predictive Coding Model (PCM) and NRT activate the limbic system to generate emotions (feelings and emotions), but each does so in its own way. In the PCM, instructions based on learned musical preferences are relayed to the limbic system to prompt it to act. With NRT, the physical resonances of neural signals originating from and corresponding to the notes of a musical source travel through excitatory pathways in the limbic system.7
Once the limbic system is activated, liking and disliking in NRT is accomplished in the same way as in PCM: by releasing neural and chemical signals that trigger embodied feelings and emotions.8 Thus, NRT is doubly embodied: resonances in sync with musical notes, and sensations felt in the brain’s body map.
Evolutionary advantage
How does an innate recognition of tone, the resonance ratios of musical tones, benefit a person? Consider these two survival values. First, speed: since some tonal combinations indicate natural danger, like a predator in a bush, a quick reflex response allows your body to react and move away before your conscious mind registers what the sound is. Secondly, attention: the world is full of cluttered background noise, and tones serve as pure auditory anchors, helping the brain filter out the static and focus on what’s important.
Wrap up
So which approach is correct: predictive coding or neural resonance theory? Do our musical preferences stem from cultural learning or biological reciprocity? The answer is probably a combination of both.
As noted neuroscientist Norman Geschwind has written, complex human behavior requires a genetic basis to execute the behavior, combined with real-world instruction and practice to enact it.9 And in keeping with the theme of this three-part series, both approaches rely on the notion of embodiment, that music is a mutual experience of our brains and bodies.
