The sound of thunder

Last Sunday (April 14) we had a series of thunderstorms roll through the region, kind of unusual for upstate New York at this time of year.  We're not particularly stormy in general, but most of the thunder and lightning we do get comes in the heat of midsummer.  On Sunday, though, a warm front brought in turbulent, moist air, and we got some decent storms and rain for most of the day.

At 11:51 AM (EDT), though, something odd happened.  There was a deep, shuddering rumble that repeated three times within the span of about two or three minutes.  (The first was the strongest.)  I grew up in the Deep South, where thunder is a frequent occurrence, and to my ears this didn't feel or sound like thunder.  Immediately I thought of a mild earthquake -- primed, of course, by the April 6 quake, centered in New Jersey, which was felt over large regions of New York and the neighboring states.

The rumble we experienced preceded the arrival of the strongest of the storms; because of that, and the fact that it "sounded wrong," I was convinced that we'd experienced an earthquake.  That conviction intensified when reports began to pour in that the same noise had been heard at the same time -- in locations separated by fifty kilometers or more.  (Thunder ordinarily can only be heard about fifteen kilometers from the source.)  

My wife, on the other hand, was absolutely sure it was thunder, albeit rather powerful and deep-pitched.

Well, let it never be said that I won't admit it when I'm wrong.

I started to doubt myself when the Paleontological Research Institution in Ithaca (only ten miles from my home) reported on Monday morning that despite numerous people calling in to report noise and shaking, their seismometer had not recorded an earthquake.  That seemed pretty unequivocal -- and after all, there had been storms in the area, even though at the time we heard the rumble, the center of the front wouldn't arrive for over an hour.  But if it had been thunder, how had a single thunderclap (or three in rapid succession) been heard over such a great distance?

The answer turns out to be a temperature inversion.  Ordinarily, temperature decreases as you go up in altitude; but this effect competes with the fact that cool air is denser and tends to sink.  (This is why in winter, the greatest risk of frost damage to plants is in isolated valleys.)  So sometimes, a wedge of warm air gets forced up and over a blob of cooler air, meaning that for a while, the temperature rises as you go up in altitude.

This is exactly what happens in a warm front; the warm air, which carries more moisture, rises and forms clouds (and if there's enough moisture and a high enough temperature gradient, thunderclouds).  But this has another effect that is less well known -- at least, by me.

The difference in density of warm and cool air means that they have different indices of refraction -- a measure of how fast a wave can travel in the medium.  A common example of different indices of refraction is the bending of light at the boundary between air and water, which is why a pencil leaning in a glass of water looks kinked at the boundary.  At a shallow enough angle, the wave doesn't cross the boundary at all, but reflects off the surface layer; this causes the heat shimmer you see on hot road surfaces, as light bounces off the layer of hot air right above the asphalt.

Sound waves can also refract, although the effect is less obvious.  But that's exactly what happened on Sunday.  A powerful lightning strike created a roll of thunder, and the sound waves propagated outward at about 343 meters per second; but when they struck the undersurface of the temperature inversion, instead of dispersing upward into the upper atmosphere, they reflected back downward.  This not only drastically increased the distance over which the sound was heard, but amplified it, changing the quality of the sound from the usual booming roll we associate with thunder to something more like an explosion -- or an earthquake.

So despite the jolt and the odd (and startlingly loud) sound, we didn't have an earthquake on Sunday.  I'm kind of disappointed, actually.  I didn't feel the one on April 6 -- although some folks in the area did -- and despite having lived in a tectonically-active part of the country (Seattle, Washington) for ten years, I've never experienced an earthquake.  I'd rather not have my house fall down, or anything, but given that the pinnacle of excitement around here is when the farmer across the road bales his hay, a mild jolt would have been kind of entertaining.

But I guess I can't check that box quite yet.  Thunder, combined with a temperature inversion, was all it was.

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Speaking beauty

My novel In the Midst of Lions, the first of a trilogy, has a character named Anderson Quaice, who is a linguistics professor.  He also has a strong pessimistic streak, something that proves justified in the course of the story.  He develops a conlang called Kalila not only as an entertaining intellectual exercise, but because he fears that civilization is heading toward collapse, and he wants a way to communicate with his friends that will not be understood by (possibly hostile) outsiders.

Kalila provides a framework for the entire trilogy, which spans over fourteen centuries.  I wanted the conlang to follow a similar trajectory as Latin did; by the second book, The Scattering Winds, Kalila has become the "Sacred Language," used in rituals and religion; by the third, The Chains of Orion, it has been relegated to a small role as a historical curiosity, something learned (and mourned!) only by academics, and which few speak fluently. 

But of course, in order to incorporate it into the narrative, I had to invent the conlang.  While I'm not a professor like Quaice, my master's degree is in historical linguistics, so I have a fairly solid background for comprehending (and thus creating) a language structure.  I've mostly studied inflected languages, like Old Norse, Old English, Latin, and Greek -- ones where nouns, verbs, and adjectives change form depending on how they're being used in sentences -- so I decided to make Kalila inflected.  (Interestingly, along the way English lost most of its noun inflections; in the sentences The dog bit the cat and The cat bit the dog you know who bit whom by word order, not because the words dog and cat change form, as they would in most inflected languages.  English does retain a few inflections, holdovers from its Old English roots -- he/him/his, she/her/hers, they/them/theirs, and who/whom are examples of inflections we've hung onto.)

One of the interesting choices I had to make centers on phonetics.  What repertoire of sounds did I want Kalila to have?  I decided I was aiming for something vaguely Slavic-sounding, with a few sound combinations and placements you don't find in English (for example, the initial /zl/ combination in the word for "quick," zlavo.)  I included only one sound that isn't found in English -- the unvoiced velar fricative (the final sound in the name Bach), which in accordance with the International Phonetic Alphabet I spelled with a letter "x" in the written form; lexa, pronounced /lekha/, means "hand."

Of course, in the end I used about one percent of all the syntax and morphology and lexicon and whatnot I'd invented in the actual story.  But it was still a lot of fun to create.

The topic comes up because of a really cool study that recently came out in the journal Language and Speech, by a team led by linguist Christine Mooshammer of Humboldt University in Berlin.  The researchers wanted to find out why some languages are perceived as sounding more pleasant-sounding than others -- but to avoid the bias that would come with actual spoken languages, they confined their analysis to conlangs such as Quenya, Sindarin, Dothraki, Klingon, Cardassian, Romulan, and Orkish.

The first stanza of a poem in Quenya, written in the lovely Tengwar script Tolkien invented [Image is in the Public Domain]

The results, perhaps unsurprisingly, rated Quenya and Sindarin (the two main Elvish languages in Tolkien's world) as the most pleasant, and Dothraki (from Game of Thrones) and Klingon to sound the most unpleasant.  Interestingly, Orkish -- at least when not being snarled by characters like Azog the Defiler -- was ranked somewhere in the middle.

Some of their conclusions:

• Languages with lower consonantal clustering were rated as more pleasant.  (On the extreme low end of this scale are Hawaiian and Japanese, which have almost no consonant clusters at all.)
• A higher frequency of front vowels (such as /i/ and /e/) as opposed to back vowels (such as /o/ and /u/) correlates with higher pleasantness ratings.
• Languages with a higher frequency of continuants (such as /l/, /r/, and /m/) as opposed to stops and plosives (like /t/ and /p/) were ranked as more pleasant-sounding.
• Higher numbers of unvoiced sibilants (such as /s/) and velars (such as the /x/ I used in Kalila) correlated with a lower ranking for pleasantness.
• The more similar the phonemic inventory of the conlang was to the test subject's native language, the more pleasant the subject thought it sounded; familiarity, apparently, is important.

This last one introduces the bias I mentioned earlier, something that Mooshammer admits is a limitation of the study.  "One of our main findings was that Orkish doesn’t sound evil without the special effects, seeing the speakers and hearing the growls and hissing sounds in the movies," she said, in an interview with PsyPost.  "Therefore, the average person should be aware of the effect of stereotypes that do influence the perception of a language.  Do languages such as German sound orderly and unpleasant and Italian beautiful and erotic because of their sounds, or just based on one’s own attitude toward their speakers?"

I wonder how the test subjects would have ranked spoken Kalila?  If the researchers want a sample, I'd be happy to provide it.

It's a fun study, which I encourage you to read in its entirety.  It brings up the bigger question, though, of why we find anything aesthetically pleasing.  I'm fascinated by why certain pieces of music are absolutely electrifying to me (one example is Stravinsky's Firebird) while others that are considered by many to be masterpieces do nothing for me at all (I've yet to hear a piece of music by Brahms that elicits more than "meh" from me).  There's an emotional resonance there with some things and not others, but I'm at a loss to explain it.

So maybe I should end with a song by Enya, which is not only beautiful musically, but is sung in the conlang she invented, Loxian.  Give this a listen and see where you'd rank it.

I don't know about you, but I think that's pretty sweet-sounding.

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Acoustic illusions

Some years ago I was in a musical trio called Alizé that specialized in traditional French folk music.  One weekend we played a gig at a local music festival, and we were approached by a very nice fellow named Will Russell who told us how much he'd enjoyed our playing -- and said he thought we should record an album.

Will is no amateur music enthusiast.  He runs Electric Wilburland, a recording studio in Newfield, New York, not far from where I live.  Will is a Grammy-winning sound engineer, and as we soon found out, is truly gifted at making musicians sound their absolute best.  He also has some nifty tricks up his sleeve, which we discovered when we were working on the audiofile for a four-tune medley we'd just recorded.

"What's your concept for this one?" Will asked.

We explained to him that the first tune is solemn, almost religious-sounding, and it gradually ramps up until reaching a peak in the last tune, a lightning-fast dance tune called "Gavotte des Montagnes."

"So we start out in church," our guitarist explained, "then there's the recessional... then there's the party."

Will frowned thoughtfully.  "Okay, for the first bit, in church.  Do you know what church you want it to be in?"

I thought he was joking.

"No, really," he explained.  "I have acoustic sampling from a bunch of different cathedrals.  Do you want to sound like you're in St. Paul's?  Or York Minster?  Or Chartres Cathedral?  Or...?"

"No way," I said.

He proceeded to play our track to us, applying the acoustics of various different cathedrals.  We ended up picking Chartres, not only because it sounded awesome, but because it seemed appropriate for a French song.

[Image licensed under the Creative Commons Marianne Casamance, Chartres - Cathédrale 16, CC BY-SA 3.0]

With all due modesty -- and with many thanks both to Will and to my bandmates -- the album (titled Le Canard Perdu) came out sounding pretty cool, and if you're so inclined, it's available on iTunes.

The topic comes up because of a paper this week in Science Advances by a team led by Theodor Becker of ETH Zürich, which has looked at the question of how we know what kind of space we're in acoustically, and then seeing if there's a way to mimic that by altering the qualities of the sound -- characteristics like reverb, interference patterns between whatever's producing the sound and the various echoes from surfaces, and so on.  The ultimate goal is to achieve whatever kind of acoustic illusion you want, from being in a particular cathedral to being underwater to having the echoes (or even the original sounds) cloaked entirely.

I don't pretend to understand the technical bits; but the results are mind-boggling.  The authors write:

[W]e demonstrate in 2D acoustic experiments that a physical scattering object can be replaced with a virtual homogeneous background medium in real time, thereby hiding the object from broadband acoustic waves (cloaking).  In a second set of experiments, we replace part of a physical homogeneous medium by a virtual scattering object, thereby creating an acoustic illusion of an object that is not physically present (holography).  Because of the broadband nature of the control loop and in contrast to other cloaking approaches, this requires neither a priori knowledge of the primary energy source nor of the scattered wavefields, and the approach holds even for primary sources, whose locations change over time.

The military applications of this technology are apparent; cloaking the sound of a surveillance device (or other piece of equipment), or creating the illusion that it's something (or somewhere) else, are of obvious utility in military settings.  As a musician, I'm more interested in the creative aspects.  The ability to create what amount to acoustic illusions is a significant step up from Will's already-impressive magic trick of teleporting us to Chartres Cathedral.

The purists in the studio audience are probably bouncing up and down in their chairs with indignation at the idea of further mechanizing the process of making (and recording) music.  I've heard plenty of musicians decrying the use of features like auto-tune -- the usual objection being that it allows second-rate singers to tune up electronically and sound way better than they actually are.

No doubt it's sometimes used that way, but I'll throw out there that like any technology for enhancing the creative process, it can be used as a cheat or it can be used to further expand the artistry and impact of the performance.  One example that immediately comes to mind is the wild, twisty use of auto-tune in Imagine Dragons' brilliantly surreal song "Thunder:"

But for innovative use of technology in music, there's no one better than the amazing British singer Imogen Heap.  Check out her use of looping for this mind-boggling --and live -- performance of her song "Just for Now:"

I've been a musician for forty years and have been up on stage more times than I can even begin to estimate, and I can't imagine having the kind of coordination to pull off something like that in front of a live audience.

So I find the Becker et al. paper exciting from a number of standpoints.  When you think about it, musicians have been experimenting with new technology all along, and not just with electronic tinkering.  Every time a new musical instrument is invented -- regardless if it's a viola da gamba or a theremin -- it expands what kind of auditory experience the listener can have.  When electronic music first gained momentum in the 1960s with pioneers like Wendy Carlos and Isao Tomita, it elicited a lot of tut-tutting from the classical music purists of the day -- but now just about everyone recognizes them for their innovative genius.  Masterpieces like Carlos's Switched-On Bach and The Well-Tempered Synthesizer and Tomita's Firebird and The Snowflakes are Dancing have rightly taken their place amongst the truly great recordings of non-standard performances of classical music.

I'll be interested to see where all this leads.  I'll end with a quote from Nobel-Prize-winning biochemist Albert Szent-Györgyi.  He was speaking about science, but it could apply equally well to any creative endeavor.  "Discovery consists of seeing what everyone has seen, and thinking what nobody else has thought."

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London in the nineteenth century was a seriously disgusting place to live, especially for the lower classes.  Sewage was dumped into gutters along the street; it then ran down into the ground -- the same ground from which residents pumped their drinking water.  The smell can only be imagined, but the prevalence of infectious water-borne diseases is a matter of record.

In 1854 there was a horrible epidemic of cholera hit central London, ultimately killing over six hundred people.  Because the most obvious unsanitary thing about the place was the smell, the leading thinkers of the time thought that cholera came from bad air -- the "miasmal model" of contagion.  But a doctor named John Snow thought it was water-borne, and through his tireless work, he was able to trace the entire epidemic to one hand-pumped well.  Finally, after weeks and months of argument, the city planners agreed to remove the handle of the well, and the epidemic ended only a few days afterward.

The work of John Snow led to a complete change in attitude toward sanitation, sewers, and safe drinking water, and in only a few years completely changed the face of the city of London.  Snow, and the epidemic he halted, are the subject of the fantastic book The Ghost Map: The Story of London's Most Terrifying Epidemic -- and How It Changed Cities, Science, and the Modern World, by science historian Steven Johnson.  The detective work Snow undertook, and his tireless efforts to save the London poor from a horrible disease, make for fascinating reading, and shine a vivid light on what cities were like back when life for all but the wealthy was "solitary, poor, nasty, brutish, and short" (to swipe Edmund Burke's trenchant turn of phrase).

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Noise alert

The week after I retired I made the mistake of saying to my wife, "I don't know what I'm going to do with all of my free time!"

Two days later we found out we had to have major foundation work done on our house.  I do mean major; erosion and settling on one corner was causing the slab to twist, and if we didn't do something, we were going to have our slab -- and almost certainly our walls -- crack catastrophically.

So yeah.  Me and my big mouth.  It's times like this I have a hard time maintaining my status as Non-Superstitious Guy.

The foundation work required that we more or less gut our formerly-finished basement.  We were already planning on redoing it, just not this completely or this precipitously.  It could be a nice space -- it's got a walk-out (we're built on a hill, which is part of what caused the problem in the first place) and with some messing about it could be a den or even a rental apartment, now that we're empty nesters and it's just me and Carol in this big house.

Me and my son working on demolition.  You can probably see the amazing family resemblance between us.

In any case, this all comes up because of a paper that appeared last week in Nature Communications  about why we perceive some sounds as unpleasant (such as shop vacs, reciprocating saws, dehumidifiers, and air filters -- all of which we had going at once down there).  And it turns out that it's not just the volume (amplitude) of the sound waves.

In "The Rough Sound of Salience Enhances Aversion Through Neural Synchronisation," by Luc H. Arnal, Andreas Kleinschmidt, Laurent Spinelli, Anne-Lise Giraud, and Pierre Mégevand of the University of Geneva, we find that the degree of perceived unpleasantness of a sound has to do with repeated peaks in "fast repetitive modulations" in the sound.  Put simply, there are two kinds of frequency most sounds have: the fundamental frequency of the tone, which we perceive as its pitch; and the rise and fall of overall loudness.  And what the researchers discovered is when that second frequency is between 30 and 150 hertz, we find it really unpleasant.  (One hertz is one vibration per second; so even 30 hertz is fast enough that we're not consciously aware of it as a repetitive noise.)

Apparently sounds in that range cause our neurons to synchronize at that frequency, heightening awareness and making them difficult to ignore.  The researchers suspect that it may be an evolved response because those sorts of noises may signal danger, but that's speculation at this point.

The authors write:

Fast repetitive modulations produce “temporally salient” flickering percepts (e.g. strobe lights, vibrators, and alarm sounds), which efficiently capture attention, generally induce rough and unpleasant sensations, and elicit avoidance.  Despite the high ecological relevance of such flickering stimuli, there is to our knowledge no existing operational definition of temporal salience and only limited experimental work accounting for the intriguing aversive sensation such auditory textures produce and the reactions they trigger.  Here, we introduce and explore the notion of temporal salience and investigate its behavioural and neural underpinnings.  Of note, although salience may not systematically result in aversive percept, we argue that in this specific context, temporal salience—owing to the imperative effect of exogenously saturating perceptual systems in time—constitutes a valid proxy of aversion.  Therefore, we hypothesise that providing fast, but still discretisable and perceptible, temporally salient acoustic cues should enhance neural processing and ensuing aversive sensation.

This discovery led to some surprising connections.  "These sounds solicit the amygdala, hippocampus and insula in particular, all areas related to salience, aversion and pain.  This explains why participants experienced them as being unbearable," said Luc Arnal, who was the paper's lead author.   "This is the first time that sounds between 40 and 80 hertz have been shown to mobilise these neural networks, although the frequencies have been used for a long time in alarm systems...  We now understand at last why the brain can't ignore these sounds.  Something particular happens at these frequencies, and there are also many illnesses that show atypical brain responses to sounds at 40 Hz.  These include Alzheimer's, autism and schizophrenia."

Which is unexpected and startling.  What is happening in the brain at those frequencies -- and how does it connect with overall mental functioning?  Does schizophrenia (for example) involve some sort of "brain noise" that is at a frequency that the sufferer can't ignore?

In any case, it's a fascinating piece of research, and on a more banal level explains why I find that shop vac so damned annoying.  At least we've got the demolition done, so I won't have any more huge messes to clean up.

Unless the universe is listening and causes some catastrophic upheaval in another part of our house.  You never know.  Just because I'm not superstitious doesn't mean I can't jinx myself.

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This week's Skeptophilia book recommendation is by the team of Mark Carwardine and the brilliant author of The Hitchhiker's Guide to the Galaxy, the late Douglas Adams.  Called Last Chance to See, it's about a round-the-world trip the two took to see the last populations of some of the world's most severely endangered animals, including the Rodrigues Fruit Bat, the Mountain Gorilla, the Aye-Aye, and the Komodo Dragon.  It's fascinating, entertaining, and sad, as Adams and Carwardine take an unflinching look at the devastation being wrought on the world's ecosystems by humans.

But it should be required reading for anyone interested in ecology, the environment, and the animal kingdom. Lucid, often funny, always eye-opening, Last Chance to See will give you a lens into the plight of some of the world's rarest species -- before they're gone forever.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Death sounds and Mexican demons

Allow me to reiterate a plea I've made more than once in Skeptophilia; would everyone just stop and learn a little bit of science and a few critical thinking skills before forwarding every damn thing you see on Facebook and Twitter?

I say this because of two stories I ran into in the last couple of days.  The first was sent to me by a friend and loyal reader of this blog -- not because he believed it himself, allow me to point out, but because he was in awe that anyone did.  It involves a claim that there's a "death sound" that is so amazingly intense that it can kill you instantly if you hear it.  Here's the direct quote:

There's a sound that is 36 octaves below middle C, that is so low that it kills you.  The sound waves literally kill you.  And this sound is only found in dark matter (for what we know).  This is so cool.

I love science!

Well, the originator of this claim may "love science," but I'd settle for less love and more understanding.  Because the number of ways in which these five short sentences don't make sense are so many and varied that it may set a record for bullshit-to-verbiage ratio.

Let's start with there being a sound that's 36 octaves below middle C.  Middle C has a frequency of 262 hertz (give or take), and for those of you who aren't physics-adept, one hertz = one vibration per second.  For each octave the pitch drops, the frequency goes down by a factor of a half.  (So one octave below middle C would be 131 hertz, two octaves below would be 65.5 hertz, and so on.)

This means that a sound 36 octaves below middle C would have a frequency equal to 262 divided by 2 raised to the 36th power hertz.  This is what is known to mathematicians as "a really freakin' small number."  Put simply, a sound wave at that frequency would correspond to one pulse of the sound passing your ear every 3,040 days.

So what we have here is the equivalent of someone shouting "WAAAH" in your ear, waiting 8.3 years, and then shouting "WAAAH" in your ear again.  The sound itself isn't going to kill you, but you might well die of boredom from waiting around for it.

Then there's the problem that it isn't the frequency of a sound that's dangerous to your hearing (or other bodily functions), it's the amplitude.  Amplitude corresponds to loudness and/or energy transfer capacity, so it's easy to see why high amplitude sounds can be dangerous.

Last, the "dark matter" part of this is just bizarre.  I tried to find out what this could possibly be about, and I did find an article about a discovery in astrophysics in which certain black holes have been discovered to create compression waves in the gas clouds surrounding them (i.e., sound waves) of extremely low frequency.  One, a black hole in the Perseus cluster, generates compression waves with a frequency 57 octaves below middle C.  (For you music geeks, apparently this means that the black hole is singing a B flat.)  No one is claiming that this sound can kill you, although being near a black hole certainly could -- and for the record, black holes have nothing whatsoever to do with dark matter.

Moving on to our other story, we have a new goofy psychic phenomenon that is buzzing on Twitter and other social media platforms.  It goes by the alliterative name of the "Charlie Charlie Challenge," and apparently has gotten so much hype that the hashtag #charliecharliechallenge is now trending.

So the idea is that there's this Mexican demon named Charlie, and you can summon him as follows.  Draw a cross on a piece of paper, thus dividing the paper into four rectangles.  Write "No" on the upper left and lower right, and "Yes" on the upper right and lower left.  Then place a pencil along one of the lines of the cross, and balance a second pencil at right angles to the first, as shown below:

Then you say, "Charlie, Charlie, are you here?"  The balanced pencil is supposed to rotate to give you the answer.

Once again, there are a variety of problems here.  First, if the pencil rotates to "No," then who's moving the pencil?  Even if this works, it's not very interesting, given that apparently all Charlie has to say is whether or not he's there.

Second, do you really think it's that easy to summon a demon up?  I'd think that demons would have much more important jobs to do, such as giving career advice to Ann Coulter.

Third, of course, we have a much simpler explanation for all of this, which is that a precariously-balanced pencil is going to be easy for stray draughts to move, as well as any other minor jostling.  So if you do this, the balanced pencil is eventually going to rotate one direction or the other whether there are demons present or not.

Fourth, a Mexican demon named "Charlie?"  "Charlie" is neither convincingly Mexican nor particularly demonic sounding.  You'd think he'd at least be called Mefistófeles or something.  Although I have to admit that saying "Mefistófeles, Mefistófeles, are you here?" is a bit of a mouthful.

So what we have here is basically a kids' game along the lines of "Bloody Mary," with the difference that we now have online social media to assure that such bullshit gets lots of traction.  

Anyhow, there you are.  Death sounds and Mexican pencil-rotating demons named "Charlie."  Further indication that the most powerful information-processing system ever built is now primarily used as a conduit for nonsensical claims and humorous pictures of cats.