Daniel J. Levitin explains what sound tells of us
Music has indubitably a special place among arts being a loyal companion of human beings: in the history we know there is not culture that was able to renounce it. As American science cognitive researcher Daniel J. Levitin says, where human beings stay together there is music: weddings, funerals, degree party, war marches, sport events, urban nights, prayers, romantic dinners, baby cradle, study, etc. Above all, music is part of ordinary life in the city and in the country, and diffusion and modalities of its consumption have reached incredible levels through the musical players of electronic era, eventually dissolved into the software and hardware of digital devices.
This Is Your Brain on Music: The Science of a Human Obsession is a book explaining the appeal of music just starting from the Levitin’s peculiar love for all its forms, a passion that addressed him among diverse but original and convergent interests, all merged into an experience and career in which circularity among entertainment, knowledge, work, study, research, innovation and desire of communication comes in evidence. The author, scholar and scientific popularizer, combines admirably severe studies – computer science, human-computer interaction, psychology, anthropology, computer music, science history – with a sound popular culture. Famous as rock musician (years ‘80), assistant and friend of international pop artists, he loves so much electric sound and its aesthetics to undertake also the job of sound engineer (Grateful Dead, Steely Dan), finally landing in neuroscientific research and direction of a sophisticated laboratory studying relations between human brain and music at McGill University of Montreal.
With a such kind of experiences it was not difficult forecasting that work would keep the proper keys to explain the emotions music reserves all of us. On the other hand, book has a modus operandi that respects the very nature of phenomenon, at the same time “superficial” and “deep”; its reflections run tackling the hardest scientific matter with wisdom and loveliness, inserting observations, stances and questions belonging at ordinary life, far away from courtly overtones in which musical publishing often falls. All that responds with proper cleverness why music, voice and sound freed by mp3 digital format insinuate themselves into the embodied flowing of our many activities.
The book interests a wide range of people – from occasional amateurs of popular music to musical experts and musicians. Nevertheless, my presentation/synthesis will privilege a more partial but general aim: just starting from a so concrete and lively base, it focuses the obscure work of physical and cultural mediation we normally entertain with our world.
A year and half ago I remained so enchanted from reading to risk signaling it for a possible translation. While I see that book’s original version has been meritoriously adopted by an Italian University (“theory and techniques of musical production in media ”), of its translation – among six ones that American publisher now advertises – I have no news. In the wait, “pillaging” Levitin’s research, I’ll try to illustrate for fans of topic some plots, begging pardon for explicative simplifications, evident fruits of my limits regarding a field that intersects so deeply biological, physical and psychological aspects. For a deep and complete argument, and for a more exact explanations and demonstrations you have, of course, the original Levitin, who I personally thank to light the obscure ravines of my “breathing music”.
Participative naturalness induced by music is the outcome of its long coevolution with human being. In certain cultures it is impossible understanding phrases as “I am not able to sing”, and in many languages singing and dancing are indicated with the same word – on the other hand, sound implies movement, and the same division between musicians and listeners is a recent idea (about 500 years). The separation in different classes has diverted us from this reality, forgetting us that we own a musical expertise unreachable even by the most sophisticated computers. Even if we often love music without knowing very much about its formal notations, this doesn’t lessen our capacity to enjoy its beauty and mystery; on the other hand, knowledge of musical formal techniques doesn’t lessen its power. If the budget for music is comparable with those of sex and drugs, its meaning and pleasure can tell us much on human brain, and, vice versa, brain can tell much on music: for Levitin, both “tell us what we really are”.
Recently, research on relationships between music and human brain has made some advancement thanks to diverse factors: neural and cognitive studies, new technologies of neural imagining, knowledge about drug properties in manipulating neurotransmitters such dopamine and serotonin, computerized neural network models. A help is also arrived from the amounts of information about patients having cerebral damages; for example, we have had evidences that musical phenomenon, although theory of division (left side of brain that coordinates language and maths, the right one art and music), implies activities of whole brain: there are people not reading written words but music, that are not able to button shirt but playing piano.
Examining the process of listening and enjoying music we are immediately put in front of the crises of the model suggesting naively an isomorphic vision of reality from our brain, while it is evident a complexity that, starting from stimuli enough simple, magnifies the obscure working of our biological and cultural body, showing us the evolutionary mechanisms, gene transmissions but, in general, coevolution between living organisms and physical world. Our brain is particularly skilled in learning through experiences, which produce durable traces into its biological structures. Every culture predisposes, and feeds itself of, a specific musical environment that becomes the mainstream for developing musical rules that inform deeply human neural circuits, above all in the more meaningful years of youth. Then, listened sound is always submitted to an exam in which brain will try to impose an order, a scheme that reflects its expectation; this is a point on which there is a strong agreement between scientists and musicians. On the other hand, musical expectation is a need based on temporal development of music that demands a continuous exercise of prediction.
If music is a set of sounds managed on the base of a mentally consolidated “legacy”, it must imply at the same time some unexpected elements to not present itself emotionally flat, and so little exiting. For evaluating music we have to understand its grammar, a rules system that canalizes it in a predictability that can, at the same time, expose it to transgression. In effect, compositors intervene just on our expectations in order to provoke emotions that alter or put forward them, disarranging partially their logics – our musical emotions are also fruits of these manipulations. Therefore, music is submitted to interpretation that is valid inside a musical grammar using to filter a subset of elementary dimensions of sound, assigning them some meanings. The mechanism looks like that of language grammar: the word cat doesn’t have anything of animal essence of “cat”, but with this set of syllables we recall its mental image. The statistical occurrences of the typical dimensions of sound – pitch, timbre, rhythm, etc. – have taught brain how they come or combine together. Our brain needs schemes to deal with similar events, to face what is common in diverse situations, and this allows it to manage incoming variations. That is valid even for music: what for us is a pure naturalness is a consequence of a culture that has developed some preferences for peculiar sounds in specific musical architecture; finally, even musical genres and styles are models that combine some characteristics mostly based on what we have already heard focusing attention of our brain.
Melody, the successive issue of notes generally repeated in refrain, is the main way to control expectations. Usually, melody notes are selected from the same musical scale. One main rule of scale tell us that brain waiting to near distance that melodic line creates among note intervals: it has a desire that notes come back “home”. Levitin notices that a great example is the immediate leap of one octave in “Somewhere over the rainbow”, a hard violation that suddenly creates tension with respect to desire of “coming back home”, a challenge that we can also find into the Pathetic by Beethoven and, with smaller leaps, into his Hymn to the joy. Then, brain is the organ that mediates stimuli perceived externally – but even internally – to offer us a representation of world. The understanding of its constitutive mechanisms is a team work between neuroscientists, that try to decipher neural codes, and cognitivists, that try to understand them at high level – not in terms of neural activations but of making abstract principles. For cognitive scientists mind contains thoughts, hopes, desires, memoirs, beliefs and experiences. At the same time, the brain is an organ of body containing cells and water, chemical and blood channels residing into the skull. The neural codes of our mental images are as bits 0,1 of digital photography. For transforming them into images computer has the software to interpret them. It’s the same for sound, and our software is the mind. Traditionally, Western culture is dualistic: soul and brain are two different things, but nowadays we have scientific proofs that thoughts, beliefs, experiences are creating through the electrochemical activations of cortical cells. When parts of brain have some damages, certain functions can be compromised. A damage over or behind left ear might cause difficulty of language comprehension; after damages at the top of head (motor cortex) fingers might lose their movements, while damages behind forehead might bring deep changes of personality – not all functions are so localized and many complex ones as patience, jealousy, etc., but even music, are distributed, often restoring themselves through a more general neural reconfiguration (neuroplasticity).
The primordial cells of brain are the neurons. The numbers describing its biology are terrific – curiously, the numerical dimensions of our micro-physics astonish as much as those of macro- physics (universe). A brain has more or less 100 billions of neurons and each neuron can activate links with other 1.000-10.000 ones. If we think that with only 4 elements there are 64 diverse combinations, and with 6 ones combinations rise exponentially to 32.768, the quantity of links – and then capacity of thoughts and states – practically becomes infinite. Then, computing and parallel processes are not only an appropriate metaphor for brain but, perhaps, also diminutive. However, it could reveal effective to introduce us with more cognition and less ingenuity into the complexity of our real perception and construction mechanisms, that mostly work inferentially and automatically for survival and speedily decision-making purposes.
Physiology and production of sound
All sound phenomenons spring from tympanum that, soliciting from movements of a physical source, suddenly actives different neurological circuits for words and music. The first ones try to distinguish consonant and vocals, the other circuits decompose signals to separate the main sound characteristics as pitch, timbre, rhythm, etc. In effect, as Edgard Varese famously said, music is “organized sound”, a result of the manipulation of a set of physical dimensions perceived through our auditory apparatus. Surprisingly, all musical events origin from vibrations of air molecules solicited from the oscillations of strings or the very movement of air volume. The brain and our internal ear have to code sound from these one-dimensional information, and this is valid also for the vision of colours rising from variations of light wavelengths. Eardrum is hit by air molecules moving synchronically with vibrations of sound. There is a part of brain, that more ancient in evolutionary terms – its lower layers – that aggregates elementary characteristics of each sound (pitch, rhythm, reverberation, duration of note, etc.), while the high part, receiving information thanks to their neural projection, engages the task of integration rising a meaning – as we had first the single letters and then their composition in words and meaningful mental images. Extraction phase produces a constant updating of information input originated from sonorous flux, and such updates imply for the high cerebral zone (frontal lobes) a though task of prediction based on: 1) what has been just heard; 2) what will come, if familiar; 3) style or genre of music; 4) what we known or deduce from music or its “contour”, for example, looking at musicians, etc.
Moreover, flux among zones of brain is two-way and the high region, depending on its elaborations, can influence throughput neural circuits the low zone; this can be a cause of illusions or other “alterations”. Top-down and bottom-up processes, and their relative integration, operating even in inferentially way to fill information gaps, elaborating a representation of reality that can also contain some alterations. There are many difficulties about sound distinction. The information arriving to receptors is undifferentiated and ambiguous; moreover, it is seldom complete and eardrum reacts to the sounds in the same way. Elaboration task must be fast and, above all, is unconscious for us: we can’t “handle” its mechanism even when well-known – Helmholtz has spoken of “unconscious inference”: Rick of “logic of perception”; Miller, Misson, Simon and Shepard of “constructive process”. Finally, we have a mental image of sound that is the result of a long chain of events, of a process that uses memorization of perceptive impressions and alterations, of a dense relational elaboration among different elements. Levitin acutely underlines that this work is capable to incredibly enrich our world thanks to the needs to fill in some way these gaps! On the other hand, some perceptive functions of brain – colours, taste, smell, listening – can even be the result of evolutionary processes and pushes that don’t exist now. It is just on such automatic mechanisms of “filling” that compositors often confide to create sonorous special effects.
The musical production involves techniques of sound creation that act peculiarly on some of its attributes or dimensions as note, pitch, rhythm, metric (pace of tune), timbre, volume, reverberation, etc. All these attributes are separable and treatable apart. Their reciprocal combination with meaningful techniques rises mental concepts as metric (the way in which notes are grouping along time), key (a hierarchy of note importance), melody (the set of consecutive notes resulting more important for our mind) or harmony (contemporary sound of many notes, that are in a precise relationship among them, as well as in a certain relation with tonal context of piece). The music is the whole of these elements and, as in painting and dance, lives in relationship with the other parts of work; finally, entire work moves together with what in that moment is not present but survives into our experience and culture.
But sound attributes don’t have the same level of importance. The pitch of note – mainly the number of vibrations per second that characterizes it – and sonorous timbre – the other characteristic vibrations associated with every note – are the dimensions more physiologically sensitive for us. The times a string or column of air moves itself back and forward in a second (hertz measures them: 1 hz = 1 movements per second) denote a peculiar sonorous event and this is the very soul of a note. These vibrations coded into neurochemical states produce the mental image of that sound. Human beings perceive only a part of frequency spectrum – it’s true also for light waves. To have an idea, human male voice oscillates around 110 hz, while female one has a double frequency, 220 hz. The lower note of piano vibrates 27,5 times for second – curiously, it is the same speed assuring us the vision of move picture – while higher note is about 4.000 hz. The pitch of sound, or its frequency, is the characteristic that mostly influences emotions: generally, low frequencies stimulate sadness while high ones provoke excitation. We say generally because association between soul states and music depends on habits that, finally, are culturally accepted because absorbed inside a certain society. Sonorous frequencies are infinite but not our capacity to deduces sound from them. This explains also why the smallest appraisable and codified distance among notes is a semitone. From a phenomenological point, we could say that both eardrum and cerebral cortex have a map looks like piano keyboard resounding with listening note. Each note has a peculiar frequency of vibration that, doubling or halving in its value, remakes the same sonority. Then, note becomes the leader of the same 12 notes that come back to repeat themselves on the high o low spectrum of audible sounds – octave concept is present in every culture.
Inside each octave every culture uses to form some musical scales constituted from notes chosen following precise criterions. We speak in terms of intervals, the distance of note from the first one of scale, inside these musical sets. It is important to underline that our aesthetical opinions about melodies are finally influenced by preferences given to peculiar intervals. First of all, every culture selects some proper subsets of notes to form musical scales utilized to build music, marking a certain experiences in listeners. Associating a certain level of happiness to major scales and of sadness to minor ones is, for example, a widely cultural matter: the actual preference for the 3rd and 5th intervals will have a linkage with the fact that even ancient Greeks had these musical preferences!
Normally, inside musical scale there is a hierarchy among notes that plays on contrasts, tensions and instability, a move that finally resolves on a sensation of stability that both first note (tonic) and fifth one (dominant) seems assuring. Even chords – a set of notes played together, chosen among notes of tonal scale on which melody runs – follow similar rules since cultures express preferences toward some chord progressions biasing the relative neural reception.
When a note plays, its fundamental frequency rises together with other ones that we could define as “spurious” (harmonics). We get so used to hear them together that, even listening the sole harmonics of a particular note, we reinsert automatically its fundamental frequency in our mind! The timbre is the other strong characteristic of sound; it depends on the level of energy that can be impressed on these “spurious” harmonics. The timbre is that dimension differentiating the sound of the same note issues from different musical instruments. Each instrument produces a diverse energetic load on harmonics, and trained musical ear can even appreciate timbre differences inside a same class of instruments. Electronic sound generators (synthesizers) “simulate” musical instruments reproducing these particular harmonic combinations. In effect, the sonorous aesthetic brought from electronic instrument depends on introduction and use of these new timbres. The importance of timbre is evident if we think how classic melodies are transformed acquiring freshness when played with such kind of instruments (the medium is the message). Other two minor factors influence timbre: attack and flux. The attack is the whole of all contingencies – techniques, uncertainties, energies, touches or “dirty” blows – that starts a sound producing other frequencies that finally will characterize each single instruments. The flux depends on the power of sound, on its temporal sustainability – it’s strong for a gong, weak for a trumpet.
The rhythm is another strongly expressive element that inherits a proper ancestral and ritual force. In effect, the playing of instrument needs neurologically the orchestration both of primitive zones – cerebellum, reptile brain – and of highly cognitive ones – motor cortex, parietal and frontal lobes, the more advanced regions of brain. People show an extraordinary skill to remember the precise metric of their preferred tunes remaining within a tolerance of 4%. If the wise orchestration of notes (frequencies), with the rule of tonal keys, melody and harmony are central for the play of emotional expectation, the rhythm that provokes movements of our feet is a guide projecting us constantly ahead, tracking an inviting path. This is in line with our way of perceiving: we need regular schemas in which being able to vary. Music intrinsically contains a pulsar mode. It is almost always regular: to produce somewhat movements it has to fire a predictive mechanism. Music pushes us ahead, and with its regular beating gives us appointments that keeps and in which we find ourselves, affirming that all is o.k. Metric is important because offers us a structure of expectations on which it is possible “eluding” o “varying” them for communicating emotions. Rhythm often is suspended: it changes and suddenly restarts. The word “groove” is used to indicate the ability of a musical piece to push us continually ahead, prolonging people in a so lovely and hardly stoppable context. Curiously, it is a quality definable only performatively, often depending on a play of drumming constituted of repetitions and small and wise differentiations, as if its execution was mechanical but with a “human” interpretation (small slides of beat, etc.)
The cerebellum is the smallest and more ancient part of brain, but its 10% of global brain volume contains 50-80% of neurons. We known it as reptile brain and it has a fundamental importance for music being responsible of timing function. It has a role in all kinds of movements, as well as in our ability to repeat them with continuity/rhythm. The cerebellum is implied in rhythm decode associating also the sensation of pleasure being directly linked with amygdale, the part of brain where emotional functions are concentrated. It has direct links with the internal parts of ear; in evolutionary terms this is an efficient way to favourite our sense of orientation taking advantage of any little noisy signals. Generally, changes into environment are speedily captured from our senses: we can see even into darkness, perceive a smallest amount of pressure on our skin and we are particularly sensitive to smell and sound.
Music seems mimes some qualities of language but gets involved us in a more primitive level in terms of motivation, pleasure and emotion. The centre of the more cognitively advanced musical functions – frontal lobes – is directly linked to cerebellum, the more primitive part (communication is two-way). Indeed, music and its neural stimuli mime life. Music – with its regularities and accidents, changes of rhythm and energetic levels – resembles better what happens in the world. Music has always been lived as an occasion of pleasure and its influence on our environment has been mostly perceived as friendly, physiologically favouring a direct dialogue between primitive and advanced parts of brain.
However, sonorous dimensions of pitch, timbre, key, harmony, rhythm, cadence, metric, etc. make sense only if we put them in mutual relation. Psychologists of gestalt were the firsts to notice (1890) that every transposed melody remains recognizable in its relations, even if modulated in other keys. Hermann Von Helmholtz taught us very much about our way of listening to, described it as an unconscious process involving inference and logical deductions. Its aim is to aggregate objects of world based on their probability of resembling and having similar behaviour respect to a certain number of common characteristics/attributions.
The grouping – the capacity of “aggregating” – is a hierarchical process depending on many factors, some ones regarding the very “objects” (form, colour, symmetry, contrast, continuity of lines and boundaries), other ones regarding psychological clues rising from our attention toward a peculiar aspect, from memory that we have of them or their similar objects, from our expectations about how they should associate each other. The mechanism of grouping is typical for sound that is fundamentally listened to in groups of notes. An orchestra is heard unitedly and only for an “act of willing” it is possible to focus on a single violin – as we do for a voice among others. The process of grouping acts also for a single note because of its many constituive harmonics; this is surprising thinking how brain put together in a coherent way the groups of harmonics of the single instrument playing in the midst of all other instruments – forming their different mental images.
Recomposition of signals is made with reference to acknowledgment schemas resident in memory: memorizing a musical composition means to internalise some constants in order to avoid that a variation of one sonorous dimension “cancels” the rest – as it could happen increasing, for example, the volume. Recomposition is for brain an operation much elaborated, so difficult that we cannot yet develop an algorithm that can recognize the different versions of the same tune – each composition is catalogued as a diverse piece. This kind of procedure should recognize the constants in the melody and rhythmic intervals trying to ignore the many other details. This great human skill is based on memory and music seems to be a special case of the theory of its operating, of which there are generally two different visions. The constructive idea sees the relations among elements as central, while memory details are filled in a second moment. The other idea insists on a perfect registration of events.
Intuitively, thinking also of gestalt theory – for which relations among elements, in this case sonorous intervals, and the more general context of listening result predominant – the first idea seems the most valid. Yet, the precision with which we remember the very intervals – as well as traces of secondary details that recall us that peculiar experience after a long period – advices to do a careful evaluation of two visions. Remembering Aristotle Levitin affirms that key is categorization. Human beings identify objects as unique aggregating them in a somewhat inclusive category. Yet, it has been discovered that boundaries among categories are much elastic existing at least three levels of aggregation. The first two ones are specialized in individuating both details of simile and the possible small differences that do not invalidate the aggregating logic. The third level, working more abstractly, is capable to make association even in presence of differences that could appear relevant. But, we should also not forget that neural circuits are so numerous that, theoretically, there is room to codify and activate mental recalling of whatever object is there-out-of-world. The memory model on which there is a certain convergence is an hybrid and speaks of a memorization based on categories building through a memory mechanism of multi-tracing.
In the creation of melody memoir memorization don’t acquire only details – pitch, rhythm, metric, timbre, etc. – but top temporal lobes (localized over ears) operate a kind of calculation regarding musical dimensions and distances of intervals, producing other parameters that will help us to recognize melody even if it is transposed. Therefore, we have both decoding and extracting of information and conceptualising of melody. The whole preserves the context and this is the reason explaining how certain stimuli (smells, sounds,…) remember us an old experience. The very meaning to have memory is to rerun our repertory of experiences. Memory does not have a precise depository: it is the reactivation of groups of neurons that – predisposed in a certain way and with peculiar values – will solicit the recovery of those memories inside the “theatre of mind”. The problem to have memory regards then the capacity to activate through certain clues the neural circuits. The fact that events impress themselves in multi-trace way implies that they are registered “blended” with a wide experiential flux, where the recall of minimal details can finally help us remembering the main event – this explains why musical experiences are so involved and linked with our life context. As secondary consequence, wider and more various our personal musical patrimony is, the more effective is the mechanism of association with selective period of our life – a limited and repeated musical repertory dilutes itself in all our experiences. We can say that music is funded on memory. It operates on listening tempting to anticipate the next note, an operation that stimulates emotional system (amygdale) that, however, is activated only when repetition is capable to recall an emotion sufficiently exciting and pleasurable.
Finally, it is useful to finish reporting Levitin’s observations about a presumed innate musical quality, a natural advantage explaining the peculiar skill of musicians. The fact that brain of musician is particularly “sound-reactive”, and even morphologically peculiar, does not explain the origin – if it is a consequence of environmental influences, genes, will, exercise, etc. The strongest evidence for thesis of an innate quality is the speed and capacity of learning; the worst one is the big role that training has in the life of a musician (quality>training>quality). Since being expert in any field is a social definition, there are comparative studies that reveal as a huge amount of continuous exercises is the common factor for a such kind of people. This is an evidence that coincides with the way how brain learns but also with the theory of a multi-trace memorization. The use and repetition of information increase probability that neural circuits for that kind of knowledge are consolidating in manifold neural states, making mnemonic image livelier because of number of times that original stimuli are experienced. Emotional aspect is also important because not only pleasure invites us to insist in learning, but mnemonic traces become richer of details for a passionately desiderate object – it can be even measured in neurochemical terms: dopamine is released to regulate emotions, and attention and humour help us to better codify mnemonic traces.
Author: Daniel J. Levitin
Title: This Is Your Brain on Music. The Science of a Human Obsession