Sound, Hearing, and the Brain
Spoiler Alert – this one is a bit dense and philosophical.
How do sound qualities arise? And how do we hear music as pitch, tone color, harmony, and melody, when nothing like these things actually exist in nature?
Sound waves go through cycles, often countless times per second. During each cycle the “amplitude” (the wave height) changes from one instant to instant. The number of cycles per second correlates with the ‘pitch’ that we hear. But in this conscious phenomenon there is no awareness at all of the loudness changing from instant to instant. As long as the frequency of the wave holds constant, the sound that we hear prolongs itself constantly through duration in time.
Thus, perceiving a steady pitch at a steady loudness is due to something that in terms of what is going on physically in nature is quite discontinuous. When the piano plays a Middle C, we do not hear a series of 261 sudden increases in loudness each second. Nor do we hear 440 sudden increases in loudness when the oboe plays its A above middle C to tune the orchestra. Something discontinuous, fitful and periodic in nature ends up as something continuous and steady in consciousness. Only when the vibration rate drops below around 20 cycles per second do we begin to hear the separate puffs of air, but at the price that we no longer hear a pitch.
What if our consciousness could run at a ‘tempo’ that allowed us to hear these individual peaks in loudness? Seconds would seem to take minutes, and small fractions of seconds would seem like seconds. The result is that the very nature of what we would ‘hear’ would be totally different: discontinuity in time would replace continuity.
This would be the equivalent in time of putting a specimen under a microscope and magnifying it in space. The greater the magnification, the less the specimen looks as it did to the unaided eye. If we were not told that it was the same object in both cases, we would be hard put to realize its identity.
Pitch, the basic substrate of all our musical perception, would disappear, and be replaced with an effect somewhat like a ratchet, or a rapid series of metronome clicks with silence between successive clicks. Gone would be the very building blocks out of which musical structure is created.
Sound: Instrumental Tone Quality versus a Chord of Pitches
Our experience of instrumental tone color (a clarinet’s sound versus a violin’s sound or versus the sound of a human voice) is, as with pitch, based on a fortunate illusion, a simplification and then recasting of sensations reaching our brain.
When an instrument, like a clarinet, plays what we perceive as a single pitch, a scientific examination of its wave form reveals something that resembles more a ‘chord’ of many pitches than what gives us the perception of a single pitch.
There is no ‘reason’ why, we might hear simply one chord versus another in the different instruments, minus any change in instrumental quality. After all, chords are part of the normal conscious phenomena that we perceive about sound. Why do we need something extra when we might content ourselves with just perceiving chords?
When we perceive what we term a chord, most often the various individual pitches in the chord are sounding with approximately the same loudness. What if the different pitches in a chord all had different loudnesses. This would add a serious level of complication. It is this extra layer of complication that the brain “simplifies” for us. What we hear is not different loudnesses among the different pitches in otherwise similar chords, but simply a different tone quality, or timbre, to the overall sound. A French horn and a violin playing Middle C produce the same chord of pitches, but the relative loudness of one pitch to another is different. How impoverished would our perception of sound be if it was bereft of this extra
parameter of tone quality. Sound would “sound” like shades of grey without any other color.
Part of the ‘illusion’ of tone quality is that we hear one pitch instead of many, and our brain casts the lowest pitch in the chord as the pitch we associate with the note, and as for the rest of the notes in the chord, depending on their mutual loudness, the brain recasts the phenomenon of pitch as the phenomenon of tone quality.
What if our brain had the ability to resolve the single sound of an instrument, at a single pitch, into a chord of many different pitches? The answer is simple. Gone would be melody and gone would be harmony.
Conclusion number two: This almost deceitful sleight of hand by the brain allows for the richness of musical structure.
P.S. Two other parameters of musical sounds, rhythm and duration, do not depend on sound to be perceivable. Duration is simply the inner experience of time in consciousness, and needs nothing external to
mark its progress. And rhythm, which in a way depends on duration, can be taught to a deaf person through a sense other than hearing: touch, for instance.
P.P.S. Of all the arts, music comes closest to being the simple conscious perception of time.
Riding the forward wave of time: catching the flow of a single note in our consciousness
Awareness of small and smaller subdivisions of time.
First, a bit of metaphysics, courtesy of the French philosopher Henri Bergson (you can skip this paragraph if you want). He says that no matter how deeply we look into smaller and smaller durations of consciousness, we never stop experiencing time as something flowing. It never stops. If anything, the closer we approach what we think is a single instant of time, the more the intensity of its flow increases and immerses us. An analogy might be the ceaseless activity on the atomic and subatomic scale that went by unnoticed until, in the twentieth century, scientists were able to take a closer look.
When we are playing piano, the very act of playing acts to distract us from the close observation of time. Our awareness of time becomes synchronized with our depression of the keys, i.e. at the onsets only of the sounds. As a result, we have a “stop frame” view of time, assuming time has flowed between one frame and the next. This is the same effect as watching a film. For all we know, between one note and the next, time itself has stopped, like the silence we hear between one click of the metronome and the next. Time resumes for us only at the onset – the “attack” – of the next note.
The attack catches our awareness again. It is suddenly louder than what is left of the sound which preceded it. The attacks are like the excited gestures of parents attempting to catch the attention of their baby so they can take a photo.
Time is thus porous to us, it has no palpable taste to us if we are trying to eat just one of the holes in a piece of Swiss cheese.
This view of time as discontinuous, and having only an implied continuity, can lead to problems for the pianist when the tempo of the music is too slow or two fast. If fast, we may not be used to paying full attention to the quality of every sound when the sounds occur in a rapid stream or spray. At a very slow tempo we may have little idea what to do while waiting for the next note to start. A whole note is a good time for a pianist to scratch an itch.
How can we ignore the “attack” sequence of time and have our consciousness penetrate into the hearts of the sounds, that is to say the portion of time after the attack during which the sound is enduring. The only answer can be to listen, and re-listen, to the sound, as often as possible during career of a single note. During the course of even a relatively short note, we can re-hear, or better, re-initiate our awareness of the sound, over and over. Even the notion of a note as a single, “solid” thing will disappear under this type of conscious awareness.
Conscious awareness is like a spotlight shown upon an object. It is like the yellow magic marker that we used in school to highlight text that we wanted to single out from the rest of the page. Even when the note is long and we re-initiate our awareness of it after a second or two has gone by, there is this curious effect. Though technically the note is getting softer and softer, at just that instant, the note seems to suddenly get a bit louder. It didn’t objectively gain in amplitude, but it gained subjective loudness due to the act of attention.
Our moments of re-awareness during the course of a single note are like moments of blowing on a fire to rekindle its strength.
Ultimately, it is not the vibration of the string that keeps the sound going through time, it is our awareness that keeps the sound alive. It is this awareness, which isn’t getting less and less as the note acoustically fades away in intensity, that allows us to connect the end of one note to the beginning of the next note with a degree of fluidity that escapes our powers when we are just trying to match one attack with another.