The Brain’s Interpretation of Sound:
The brain has fascinated scientists and researchers for hundreds of years of documented time relevant to our discussion. In 2019, we have a tremendous volume of research to help us understand why our brains and bodies respond the way they do to the world around us. I am oversimplifying and including only the relevant sections of this complicated body of research to help us understand those pieces that are most useful for our purposes.
Physical, Chemical, and Psychological Elements of Listening and Participating in Music
Our work today will focus on the pathways for processing sound as it moves through the brain. I will include additional diagrams for your reference as we progress through this work, and you may flip between them to promote understanding at your leisure.
How the Brain Hears a SoundIn order to hear a sound, sound waves must enter our ear and be translated from WAVE energy into an ELECTRONIC impulse in order for our brain to be able to interpret the sound.
The breakdown of sound processing in the ear:
- Sound waves in the air enter the ear canal.
- When they hit the ear drum, it vibrates according to the waves hitting it.
- The tiny bones in the inner ear move in time with the ear drum like little levers.
- The inner ear bones transfer the wave energy to the fluid inside the cochlea, which causes the hairs inside to move.
- The motion of these hairs is picked up by the auditory nerve, which translates the information electronically to the brain.
How does the sound get from the ear into the brain?
- Once the auditory nerve has created an electronic signal, the sound is sent into the Primary Auditory Cortex (PAC).
- Inside the PAC, there are a series of neurons that are constantly firing. In silence, they are all moving all the time. Even when you are asleep. Even now.
- Each neuron is specific to a very tiny piece of the electronic message.
- When the electronic signal is delivered to the PAC, the neurons whose signature matches that of the sound stop moving.
- How does that make sense? The hairs in the cochlea are not moving unless stimulated. When one of those hairs is moved, the neuron in the PAC, which is always moving, stops moving, almost like there were a string between the two and only one can move at a time. Imagine the hair in the cochlea pulling the neuron in the PAC when the right sound wave hits it to stop the neuron from moving.
- This is the same way we see color, only their resting state is one devoid of motion. The rods and cones exist naturally at rest, and only the ones designed to respond to the wavelength will react to the light entering the eye. The others stay at rest.
- That’s how the sound gets into the brain.
- The hearing of the first sound, a single wave, if you will, does not lead the brain to any interpretation beyond identifying the source of the sound. A single sound will create a sense of anticipation while the brain awaits another.
- When a second sound is received, these signals enter the Secondary Auditory Cortex, or Auditory Association Area, where the brain then decides upon the relationship of the sounds to one another.
- Skipping some details and simplifying for the sake of time, the sounds are processed simultaneously in the left and right brain.
- The Right Brain focuses on the simultaneous sounds (sustained chords, overtones, droning notes, etc.) while the Left Brain focuses on each note as an individual and how it relates to the others to assess things like duration, rhythm, tempo, and tonality. Your brain literally writes sheet music, the right brain completing the score for the left hand, and the left brain composing the melody.
- Our brains do not store large pieces of information as one block, choosing to store smaller pieces which enable us to recognize the things we hear in fewer signals. Imagine the difference between recognizing Beethoven’s fifth with those first three notes compared to having to hear the whole song before it clicks!
- The fractionation of our stored melodies is why a run in one song may remind you of another seemingly unrelated song.
- Our brains don’t like to store information they are not using; alternatively, the brain wants to use everything that is has in storage. No information is useless!
- When you hear a series of sounds, your brain will take ALL the information that comes along with that piece of melody and shove it into your Frontal Lobe, which is sort of like the brain’s white board.
- This information is then packaged and sent to the Hippocampus where our emotional responses and generalized experiences live. The Hippocampus helps us decide what parts of our past experiences need to be sent to the Frontal Lobe/White Board intertwined with the classification of all that stuff in the Temporal Lobe.
- The Limbic System makes use of our knowledge of the world and weighs the importance of every factor to direct us toward the appropriate response. You’ll get the list of songs this might be, plus the list of the places you’ve been when you heard those songs, the people with were with (or wish you were with), and ALL the emotions you’ve experienced when you heard anything similar.
- This list of potential responses is known as Anticipations.
- Anticipations are the series of things your brain is expecting to happen next, and this is not limited to the next phrase of music. The brain has stored for you a series of hierarchies that are all the possibilities that may come next in order of likelihood or more likely to cause you harm.
The Auditory Cortex is very close to the Pain and Anticipation of Pain centers in your brain. Why? Once upon a time, humans relied on fight or flight to help them stay alive. We learned to recognize sounds and store the associated safety information:
- Tiger growl? Flight.
- A smaller/prey animal? Fight.
- A baby cry? Neither, you’re safe, go help the baby.
A slamming car door can either be,
- “Yay, my partner is home!” OR
- “Why did that door get shut so hard? What mood is my partner going to be in when they come inside? I better make sure the kitchen is clean, and did I finish everything they asked me to do today? Oh no, dinner isn’t completely done yet. I hope they don’t mind pork chops. Ack! These may be a little overdone. Oh shit….”
When a sound hits the Frontal Lobe with all its associated baggage, it is held there for resolution, which will be deemed negative or positive based upon how well the anticipation is or is not satisfied. Did the next sound meet our expectations? When a sound doesn’t meet our expectations, this results in a discrepancy. Antonio Damasio describes Discrepancy Theory in his work, Descartes’ Error. He concludes that all emotive responses are a result of an anticipation that either exceeds or falls short of our expected result.
Anticipation and ResolutionMusic is a series of anticipations that we expect to resolve themselves based on our society’s ethno-musical harmonic paradigm. There are certain notes we expect to hear because of what we are used to hearing.
Say we hear a C major chord: C, E, G, respectively, as the base chord. When we hear a D, we anticipate that the D will resolve itself to a C or an E, but hopefully a C. Likewise, if we hear an F, we anticipate it will resolve itself to a G. We want everything that meanders about to land back on our base chord, to resolve itself in the manner we anticipate. That makes us happy. The farther away we meander, the happier we are when the resolution comes. These are the ways a masterful composer will build anticipation and leave the listeners in pleasure and approaching a state of ecstasy: by creating anticipations in the listeners and then meeting their every desire.
Alternately, a minor chord, a chord in which the center note is dropped ½ step, such as C minor: C, E flat, G, elicits sadness because the overtones do not resolve as we anticipate. It leaves us just shy of our goal. If the base chord carries an accidental, a note that falls outside of the key signature, the dissonance created will make us angry or increase adrenaline-based responses. Dissonance is not an easily accepted resolution!