The acoustics of concert halls and my living room

Music and Brain Blog #1
Brian Graiser

Jourdain, Robert, Music, the Brain, and Ecstasy, HarperCollins Publishers, NY, 1997. Chapter 2: …to tone…, subsection “Concert Halls,” pgs. 46-51.

Synopsis: Often overlooked in importance by audiences, the concert hall acts as an acoustic resonator for the instruments played within, and could therefore be considered an extension of those instruments. Soloists and ensemble conductors must thoughtfully adapt to a particular hall’s resonance, temperature, humidity, and other factors in order to produce the best possible sound. The nature of unrestricted sound is to spread out in all directions and dissipate quickly; by controlling the path of the sound through surface materials and positions, concert halls make it possible for sound to travel all the way to the back of the audience without losing too much intensity. There are three kinds of sound that concert hall acousticians are concerned with: direct sound, which travels directly from the performers to the audience; early sound, which is comprised of the initial sound reflections from the walls and ceiling reaching the audience; and reverberation, which is composed of the subsequent echoes and sound reflections heard after the early sound. A venue is considered “intimate” when the first reflections of the early sound reach the audience no later than 0.02 seconds after the direct sound; this quality is impossible to produce in a larger concert hall due to the wide space and vast walls and ceilings, so it is typically reserved for solo or chamber concert venues that are smaller in nature. Conversely, while reverberation is a rare occurrence in nature or smaller venues, its prominence in large concert halls was a key factor in the development and evolution of large ensembles such as symphony orchestras; the longer resonance led to a new concept of harmonic blending and progression that was inconceivable in a drier, “intimate” room. Acousticians consider a sound’s reverberation to have stopped once it has dwindled to one millionth of its original strength, and as such can be used as an ideal measuring tool: it is desirable to achieve one second of reverberation for chamber music, 1.5 seconds for early Classical or minimalist large ensemble music, and as much as 2.25 seconds for lush Romantic symphonies. However, the majority of music listening today occurs at home, not in a concert hall. The smaller room delivers a high degree of intimacy, but the reverberation is warped; the numerous objects and surfaces in the room produce a stronger-than-usual intensity in the reverberation, but also cause it to disappear within 0.5 seconds. To solve this problem, most recording studios add in synthetic reverberation to their products; however, these false reverberations are compounded when introduced to an irregular venue (such as a living room), further distorting the sound from its original form and quality.

Reflection: The physics of acoustics and resonance has always fascinated me; as a percussionist, I deal with the acoustic properties of marimba resonators and timpani bowls on a daily basis, so I really don’t have much of a choice in the matter. However, one thing that has really gained my interest is the science behind why certain halls make certain percussion instruments sound much better than others. While Walter Hall is a great venue, it can also lend a dryness to some ensembles, and a lushness to others. Perhaps this is a product of sound directionality and performer positioning; many concert halls have a spatial threshold, where performers beyond a certain point of the stage do not get “picked up” by all the reflective surfaces of the hall. Another thing to note is that unlike most wind instruments or vocalists, most percussion instruments project their sound straight up (excluding instruments such as bass drums, which are purposefully angled towards the audience); the sound from a marimba or vibraphone bar travels down into the resonator tube, hits the cap at the end, and is reflected back up towards the ceiling (inexperienced personnel do not know this, and as result many microphones are erroneously placed underneath the bars of the instrument, rather than above them).

Another thing that piqued my curiosity was Jourdain’s condemnation of recording techniques aimed at the home market. I wouldn’t go so far as to say that living rooms “ruin” music recordings, but it’s obvious that the sound quality experienced in a concert hall seat is much different than that experienced on my couch. In terms of mass marketability, adding in false reverb in the editing phase of a recording makes sense; it gives a vague sensation of being in a larger room, and adds a degree of resonance that would not naturally occur in the average living room. However, for the true audiophiles out there, isn’t there a better option?

I had a thought (a potentially expensive one, but worthwhile in my opinion): what if recording engineers placed more microphones in various locations of the concert hall during a recording session, and focused less on capturing the immediate, intimate sound that occurs on the stage itself? Beyond the standard “ambient sound” microphones, I would be interested in seeing what would happen if an array of two dozen or so microphones were spread throughout the hall (particularly in the “sweet spot” of the audience, which is typically the middle of the mezzanine level), and only a handful of microphones were actually placed on the stage with the musicians. From there, studio engineers could mix the levels to create the desired balance, but they would have many more sources of early sound and reverberation in relation to the usual abundance of direct sound. Transfer those properties to a 5.1 surround sound speaker system, with the rear speakers assigned to only producing the appropriate reflections of early sound and reverberation, and I believe one can create a much richer and more realistic listening experience.

Musicians slightly crazy, but smarter?

Reference
Gibson, C., Folley, B. S., Park, Sohee (2008). Enhanced divergent thinking and creativity in musicians: A behavioral and near-infrared spectroscopy . Brain and Cognition, 69(2009), 162-169. doi: 10.1016/j.bandc.2008.07.009.

Summary
The purpose of this study was to examine creativity as demonstrated by divergent thinking and to link it to personality traits, intelligence (IQ), and activity in the frontal cortical regions of the brain, which have shown increased activity in association with creative (divergent) thinking.

Divergent thinking has long been seen as a component of creativity as it requires flexibility in thinking and problem solving, in particular, the ability to guide one’s thoughts without clearly defined parameters. Interestingly, in a previous study, people displaying more schizotypal personality traits also showed greater activity in the frontal cortical area of the brain, demonstrating a link between creativity and psychosis-proneness.

Musicians are seen as highly creative people, so the authors of the study recruited 20 classical music students and 20 non-musicians for two experiments. All participants were assessed for intelligence, handedness (fine motor skills in each hand), and verbal fluency. They also filled out questionnaires regarding creativity and schizotypal personality.

EXPERIMENT #1:
a) Remote Associates Test (RAT) – Participants were given three words and were asked to find another associated word. They could generate as many words as they want but there’s one correct answer.
b) Divergent Thinking Test (DTT) – Participants were asked to generate uses for objects alone and in combination with others. There was no time limit and they could come up with as many uses as they wanted.

EXPERIMENT #2: (used a subset of the original group: 8 musicians, 7 non-musicians)
Near infrared spectroscopy (NIRS) was used to measure blood oxygenation changes in the frontal cortex during a modified DTT.

RESULTS:
Musicians self-reported greater creative and schizotypal traits in the questionnaires. Musicians showed higher levels of divergent thinking and IQ (including verbal). There was no difference in handedness between groups. Musicians scored better on both the RAT and DTT. Musicians showed greater activity in both sides of the frontal cortex whereas non-musicians showed more activity in the left side.

Reflection:
This study, by the authors’ own account seems to provide greater credence to the idea that music makes you smarter. Musicians also seem to be more creative and think more ‘out-of-the-box’ than non-musicians. Perhaps a bit more disturbing is the link to psychosis-proneness, though musicians in this study did not achieve clinical levels. It’s also not the first time that higher IQ has been linked to mental health concerns (click here for an example).

Musical training certainly encourages an expansion of the imagination, and even without knowing that music causes activity in many areas of the brain, it’s easy to recognize the full-body involvement it calls for, not to mention the emotional element that factors into the equation. Divergent thinking may be an outcome of our need to draw from diverse thoughts and experiences----tactile, sensual, emotional, etc. It makes sense that the cognitive-perceptual part of the schizotypal questionnaire has to do with “perceptual aberrations and magical thinking”. I’m not sure what they mean by magical thinking, exactly, but what else to we do when we write, improvise, or interpret a piece, but conceptualize the world in ways that others may not?

I do wonder, however, whether musical training can cause a greater manifestation of these traits, or whether those predisposed to toward these traits and ways of thinking gravitate toward music and other arts.

“Williams Syndrome: A Hypermusical Species” from Oliver Sacks "Musicophilia"

Summary - Oliver Sacks writes about Williams Syndrome (known as Williams-Beuren syndrome in Europe). These children and adults are a fascinating group of individuals who love music and love people. Generally, they have an IQ of less than 60 but are articulate. Sacks talks about one young girl (14) who describes an elephant’s appearance and personality in great narrative detail, but cannot draw an elephant that is recognizable in any way. In his book, Musicophilia, Sacks juxtaposes the writing with the drawing (p. 360), and the contradiction between cognitive skills is glaring. Williams children have difficulties with other tasks such as stacking blocks, adding numbers, the ability to tie their shoes or “judge obstacles and steps” (p. 359).

They are very social and engaging even to strangers, meeting their gazes, grabbing their hands, encouraging them to join in the activity at hand. This sensitivity is also evident in their music. They love music and can spend hours absorbed in it and react very emotionally to it. Their precocity in musical abilities is a common thread although only a few may become professional musicians. Sacks summarizes their personalities, “The three dispositions which are so heightened in people with Williams syndrome – the musical, the narrative, and the social – seem to go together, distinct yet intimately associated elements of the ardent expressive and communicative drive that is absolutely central in Williams syndrome” (p. 365).

It is quite rare to have Williams syndrome (1 in 10,000) and it wasn’t until 1961 that cardiologist, J.C.P Williams wrote about it (p. 365). Williams syndrome children and adults have heart and vessel defects. Another similarity is their facial appearance, which is sometimes described as ‘elfin’ with upturned noses, large eyes, small chins and round eyes. Williams syndrome children and adults have a tiny chromosomal deletion of 15-25 genes on one chromosome – which is “less than a thousandth part of the twenty-five thousand or so genes in the human genome” (p. 367).

Through brain imaging and a small number of autopsy reports, some discoveries have been made about Williams syndrome brains. Their brains are generally about 20% smaller than normal brains and the weight is distributed unevenly with the weight and size predominantly at the front of the brain. This disadvantages the occipital and parietal lobes but benefits the normal or “supernormal” (p. 365) size of the temporal lobes. The primary cortex is larger and “there seemed to be significant changes in the planum temporale – a structure known to be crucial for the perception of both speech and music, as well as for absolute pitch” (p. 366).

Another interesting difference in their brains is where they process “musicality” and emotional responses. In a comparison of Williams syndrome individuals, ‘normal’ individuals and professional musicians, it was discovered that Williams syndrome brains use a “wider set of neural structures to perceive and respond to music, including regions of the cerebellum, brain stem, and amygdala which are scarcely activated at all in normal subjects”. The active amygdala is thought to be responsible for “their almost helpless attraction to music” (p. 366). Some of the chromosomal and brain differences can account for the cognitive talents and problems exhibited by Williams syndrome individuals; however, questions remain that are still being researched. Some unknowns may be answered although some may not.

Reflection – Oliver Sacks opened this chapter by describing the summer camp in Massachusetts that he visited in the summer of 1995. This is the place that he first met Williams syndrome children and young adults, a place where he was immediately accepted and embraced. As he started to describe it, I thought about the fairly recent movie Camp Rock starring the infamous Jonas Brothers and Demi Lovato (at least in the tween world). It was based on the story of a summer camp, just like the real one, where young adults gathered for fun, camaraderie, and music. I thought about how it really was more the same than different, if Camp Rock had been a real summer camp and not full of Hollywood stereotypes and perfect hair. Then again, perhaps the musical ability and passion would have been greater in the real summer camp in Massachusetts. And if you live with a rare condition, it might be hard to find others that can relate to you, share your experiences, your struggles, your triumphs. I imagine, although I can't possibly claim to know, what a summer camp experience of like minds could mean for Williams syndrome individuals, family, and friends.

The stories of these children and adults described by Sacks are charming and engaging and amazing all at the same time. I was struck by the stark contrasts in their cognitive abilities, gifted and problematic at the same time. We are fortunate to live in a time when technology allows us to see how parts of the brain react to situations such as in the musicality-emotional response research. It shows that Williams syndrome brain processing is very special and unique. I recognize the impact of the differences in the brains, but also that a tiny chromosomal deficiency can make such an impact is ‘huge’ in my mind. We are truly complex and sophisticated beings and it is astounding how many babies are born each year without complication. I know that I comment in almost every blog on the marvel of our physiological and psychological being, but how can you not.