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."

 **************************************

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!]

Squatchius invisibilis

There's a general rule about claims of the paranormal, vis-à-vis the amount of hard evidence thereof, and on first glance it's a little counterintuitive.  It would seem that the likelihood of such claims being true would be directly proportional to the number of people who say they've seen whatever it is -- ghosts, UFOs, Bigfoot, or whatever.  Assuming equal (and low to nonexistent) hard evidence in favor, the only thing we have to go on is eyewitness testimony, and the more there is of that, the better supported the claim is.

Right?

In fact, it is exactly the opposite.  The likelihood of a bizarre claim being true, in the absence of evidence, is inversely proportional to the number of eyewitness claims.

Let's take something for which we have exactly zero tangible, scientifically admissible evidence -- Bigfoot.  We hear cries of indignation from Squatchers that we skeptics are being unfairly dismissive.  "How can all of the eyewitness accounts be wrong?" they say.  And it sounds reasonable -- at first.

But think about it.  Let's accept, for the moment, that the Squatchers are right, and there is a large proto-hominid species out there -- with a large enough population not only to be reproductively viable and stable, but to give rise to frequent sightings.  (And if you want to see how many sightings do get reported every week, just check out sites like Bigfoot Field Journal.  You'll be astonished.)

So, we've got thousands of very large animals out there, being seen every week -- and not once, never, has one of them left behind a carcass, a clump of hair, a bone, or a tooth demonstrably of proto-hominid origin?  With that many eyewitness sightings, there should be at least one incontrovertible piece of hard evidence by now.  That there isn't is fairly damning.

In reality, of course, a rare, intelligent, wary cryptid should produce almost no sightings at all.  Look, for example, at how infrequently people see bobcats -- a shy, nocturnal species that is also amazingly common.  There are an estimated 30,000 bobcats in New York state -- which, in 2006 and 2007, resulted in only a little over 100 sightings each year.  I've lived for over twenty years in a rural part of upstate New York, spent lots of time out in the woods, and I've never seen one.

So really, what's relevant here is the evidence:sightings ratio.  The lower that is, the less likely the claim is to be true.  If there are thousands of eyewitness claims, and very little hard evidence, the conjecture can effectively be dismissed, because the evidence:sightings ratio is damn close to zero.

Of course, that's a serious blow to the Squatchers, and these are not folks who will take such a thing lying down.  The Bigfoots have ways of not being seen, they say.  They bury their dead -- thus, no bones, no teeth, no skins.  Beyond that, things get even wackier.  A Squatcher named Linda Jo Martin thinks that the reason they get away is that they're telepathic, so they hear our thoughts as we approach and escape, especially if we were intent on capturing or (heaven forfend) shooting one.  Another Squatcher, the amusingly-named Kewaunee Lapseritis, thinks that the Bigfoots are not only psychic, they're in contact with space aliens, and get away on spaceships if they are in danger.

But that's bush league crazy compared to what I came across yesterday, advanced as a serious claim on the wonderfully wacky site Cryptomundo; the reason we can't find Bigfoots, or any hard evidence thereof, is because they've developed cloaking ability.

If you're like me, your first thought was, "No, that's not Bigfoot; I believe you're thinking of the Klingons."  But it appears that they're serious.  Here's a direct quote:

One of the most heated subjects of debate in the bigfoot world is about the possibility that the creatures elude us so well because they have some kind of “cloaking” ability that no other creature is known to possess. Some witnesses claim this ability is in fact real, while others scoff. But most, like me, just want a clear answer…and some visual proof wouldn’t hurt either.

This demands that we ask the question of how you could have visual proof of something that can become invisible.  But that thought evidently never occurs to them, as the author goes on to describe a... well, I guess I'll call it a "sighting," for want of a better word... by a fellow named Dave Moser in North Carolina:

Our group was on a planned walk down a hard packed dirt trail, south of our camp. Many in the group have had BF experiences on this tail before which parallels a ridge to the west and east so you are walking in somewhat of a valley. A team of 6 had left the campground around 2330 and may have gone close to a ¼ mile down the trail when I observed the 4 team members who were approximately 70-80 yards ahead of me had stopped and were looking to the west or right side of the trail. It’s customary for me to stop and observe the area with my Thermal camera from the rear of the group. I prefer this position because I like to scan behind us to see if anything is following and it also gives me a wider angle of view of what the front team may be observing. The 5th team member was approximately 8-10 feet ahead of me and had G3 night vision binoculars. I noticed that one of the front team members had stepped a few feet off the road in the woods. He was also using a thermal imager but did not have any noticeable heat signatures that I know of. After talking to him yesterday to find out the reason he had stopped he provided the following statement:

“I hear something moving to the left of trail. What at first was a deer making a distress call and then thumping noise like someone or thing was stomping its foot. I do not think it was a deer making the stomping noise. When I walked off the trail and staying by the tree, I felt like I was being watched. I had a sense that whatever it was it was now in front of me about 50 yards.”

Nothing was observed or heard during the brief stop at 12:03am early Saturday morning but upon review my first indication to there being something there was the leaves shuffling. I knew right away that no one was in the woods to the left or right of me so a rewind was required. The rest of the midnight hike was uneventful except for the return trip to camp. One of my team members usually has an EMF detector on his persons and as we passed the spot where the figure was captured on the Thermal and about 50 yards north his EMP detector went ballistic, I mean a full pegged out hit that lasted for close to a minute beeping loudly. Although nothing was ever seen or discovered to cause the deflection it was a strange coincidence to say the least!

To Moser's credit, he states outright that he doesn't think this was a "cloaked Bigfoot," although how anyone can even type that phrase without guffawing is beyond me.  For one thing, if an animal can turn invisible, how could it see?  Its eyes, including the lens and retina, would suddenly have the same transparency and refractive index as air, meaning that light would go right through them.  (Right through its whole head, in fact.)  So if Bigfoot can turn invisible, it would also become instantaneously blind, which would explain why it was shuffling through the leaves and bumping into things.

On the other hand, why am I even addressing this seriously?

No, I don't know, either.

A photograph I took in Colorado.  There is an invisible cloaked Bigfoot in the lower right of the shot.

The bottom line is that if your evidence:sightings ratio is so low that you have to make appeal to telepathy, UFOs, or advanced cloaking technology to explain to skeptics why you don't have the goods, then you should probably just give up.  Harsh, but realistic.

Spend your time looking for bobcats, instead.  They're really cool-looking, and as an added bonus, they actually exist.