Some Entertaining Bullshit about Echoes Echoes Echoes

by Bradley Denton

         The aphorism “I’ve suffered for my art – now it’s your turn,” when applied to science fiction writers, usually means that the writers have done so much research on the scientific or technical aspects of their stories that they can’t resist inserting long passages containing the details of that research into the stories themselves . . . whether or not those massive info-dumps (or “big chunks of bullshit”), as entertaining as they may be, enhance plot or illuminate character.  (The key word here, most likely, is “not.”)

         The plots and characters of my own stories tend not to depend too heavily on science or technology, which has prompted some observers to question whether I’m a science fiction writer at all.  Nevertheless, I do have a tendency to research the ever-loving bejeezus out of any topic even slightly related to a story-in-progress.  There’s a good reason for this:  As a tactic for avoiding actual work, research is right up there with rearranging the furniture, cataloguing your grandparents’ National Geographic collection, or giving your cat a perm.

         Such was the case while I was writing my Wild Cards story “Echoes from a Canyon Wall” (PAIRING UP, ed. GRRM, Bantam, 2023).  It’s a novelette featuring my loudmouthed character Freddie “Amplifier” Fullerton and Caroline Spector’s character Juliet “Ink” Summers, with special appearances by Caroline’s character the Amazing Bubbles and the late, great John Joseph Miller’s character the Midnight Angel.  The plot of the story involves, among other things, a canyon and echoes.  So I proceeded to research the ever-loving bejeezus out of both canyons and echoes, as well as all possible intersections between them and permutations thereof.  As a result, I spent way, WAY more time reading about those subjects than you’ll spend reading the story – which, now that I mention it, is time that will fly right by, pretty much like whatever time you spend eating ice cream.          

         That’s because I included none of my canyon-and-echo research (or “big chunks of bullshit”) in the story itself.  Well, virtually none.  I suppose maybe a little of the research about canyons did make its way into the final draft.  (Spoiler Alert: Canyons are deep, and contain rocks.)

         But you’ll find nothing in the story about the scientific or technical aspects of echoes, even though some echoes occur in the story.  After all, once you’ve heard an echo, as almost everyone one one has has has, you get the gist, and there isn’t much more to explain.  Also, the basics of how an echo works (sound waves, distance, hard surface, reflection) were covered back in grade-school science.  Or at least, they used to be.  For all I know, schools are now teaching that sound waves are caused by the beating of angels’ wings, and an echo is what happens when an angel smacks into a vertical surface, like a grackle hitting a window.  (Which is something the Midnight Angel would never do.)

         So you may worry that I’ve exhausted the topic of this post while just getting started – except, as some of you may recall from my earlier post “A Brief History of Loudness,” natural phenomena are only the beginning of the story when it comes to sound.  It’s when humans start devising their own uses for – and artificial versions of – those phenomena that things get more interesting.  Or at least, noisier.

         The most obvious practical human application of echoes is echolocation.  Various other animals, like bats and whales, have their own built-in versions of echolocation thanks to millennia of natural selection (or, if you prefer, “being smacked into by angels”).  But human beings, with our big brains and impatience, didn’t want to wait that long.  We opted for invention over evolution and came up with things like sonar (an acronym for “sound navigation and ranging”), which can work in both air and water, but – because of how sound waves are affected by different media – works much better in water.  (On the other hand, radar, or “radio detection and ranging,” because of how electromagnetic waves are affected by different media, works much better in air.)  

         Since we know how fast sound waves move in water, we can send out a ping and then determine the locations of underwater vessels, pods of dolphins, and Prince Namor, the Sub-Mariner, just from the timing of the echo.  In fact, sonar can be so accurate that some varieties are able to provide complete images of underwater objects (submarines, shipwrecks, lost cities, Prince Namor) just by bouncing sound waves from them.  It’s also this same basic technology that allows an ultrasound technician to image your innards.  Your gallbladder has an echo, which enables the ultrasound machine to assemble a picture of it.  And as long as I’ve already referenced one Marvel Comics character, I’ll point out that this same principle is also how Daredevil, though technically blind, can “see” the bad guys whose asses he whups.

         Human beings, though, aren’t only interested in the practical applications of a thing.  In fact, the practical applications of a thing are just at the top of the list for a small subset of the general population – scientists, engineers, technicians – commonly known as “nerds.”  What really gets the blood pumping for a much larger percentage of human beings, or “the cool kids,” is . . . well, entertaining bullshit.

         As long as people have been entertained by making noise and/or music (which is probably as long as there have been people), echo and reverberation have been highly desirable, because they sound awesome.  Cathedrals weren’t built to be utterly cavernous, with ridiculously high ceilings, just because God is (one assumes) freaking huge, like Galactus after chowing down on a few planets.  No, it’s because when a pipe organ and choir start jamming on “Inna Gadda Da Vida,” the reverb (or, if the cathedral is cavernous enough, the echo) in there is terrific.

         At this point we need to get a little nerdy ourselves, just for a moment, and distinguish between the terms “echo” and “reverb(eration).”  Echo and reverb are quite similar, but also completely different.  Basically, if you shout at a canyon wall, or inside a tunnel, or from the choir of a cathedral, and the sound takes more than about a tenth of a second (100 milliseconds) to get back to you, you’ll hear it as a copy of your original shout – that is, as an echo.  That’s because the perception of a sound only lasts in most people’s brains for about a tenth of a second, and you’ve stopped hearing your original shout before its reflection gets back to you.  But if your shout takes less than a tenth of a second to return, you’ll still be hearing your original shout, and the returning sound will combine with it.  So rather than hearing a separate copy, you’ll hear your original shout prolonged – that is, reverberating.  And the magic canyon-wall distance from which the returning reflection of your shout will begin to morph from reverb to echo is about 17 meters, or just under 56 feet.

         Of course, all of that only applies if the walls or ceiling are constructed of a hard material like stone, or are covered with a hard material like ceramic tile.  (This is why you get such great reverb singing in the bathroom.)  The echo and reverb calculations change dramatically when you have various non-reflective, sound-absorbing objects – trees, curtains, furniture, carpet, the Avengers (except for Cap’s vibranium shield, which will totally reflect sound), etc. – in any given space.  The architects and engineers who design concert halls often expend tremendous effort to take all of that into account, and boy, can you tell the difference when they don’t.  Too much reverb or echo can turn music to cacophonous mush, and too little can make it sound as flat as roadkill.

         This is why sound-engineering nerds, bless ‘em, have done what human beings have always done when the natural world and natural spaces become too complicated:  Invent artificial solutions that are just as good, or maybe even better.  And those solutions are especially useful when it comes not just to the performance of music, but to recording it.

         In the case of reverb, the earliest music-recording solutions were simple:  put the musicians in a fairly reverb-free room, and pipe the sound they make to a speaker in a separate room with tiled walls.  Stick a microphone in that tiled room, placing it in whichever part of the room gives you the amount of reverb you want, and then pipe the sound it collects back to your recording console.  If you have to, you can even adjust the reverb in the tiled chamber with sound-absorbent panels, curtains, or blankets . . . or with additional sound-reflecting or sound-diffracting walls and columns.  (Sound diffraction occurs when a sound wave moves around an object either smaller than or equal to its wavelength.)  And yes, such chambers can also be large enough, or designed with enough additional reflecting and diffracting objects, to produce actual echoes (hence the term “echo chamber”).  But all you really need is a narrow 56-foot-long room with a speaker and a microphone at one end, and a tiled wall at the other.

         So how did those reverb chambers sound on finished recordings?  Pretty great, in most cases – so much so that some professional recording studios, especially long-established ones, still use them.  For example, the famous Abbey Road Studios in London has three reverb chambers, one for each recording studio.  So if you like, you can hear how a genuine chamber reverb sounds on, I dunno, maybe the Beatles’ Abbey Road.

         Clearly, though, a big tiled room isn’t ideal for anyone who doesn’t have the space or money to build one.  So it didn’t take long for the nerds to come up with more compact solutions, which required some pretty clever gadgetry in the days before digital technology made things easier.  And their first attempts weren’t always what one might call truly compact.  They were, after all, trying to replicate the sound of an entire room.


         For example, one of the first “compact” solutions for creating reverberation, “plate reverb” was a large sheet of metal, often about 7 feet long by 4 feet wide or even larger, suspended in an enclosed frame and looking like a big hunk cut from the wall of someone’s garage.  But it worked in a way similar to the way room reverb worked:  The electromagnetic signal from the studio was pumped into the plate, driving it as if driving a speaker cone.  But on that big, flat plate, the resulting vibrations undulated back and forth across the metal and collided with each other like the sound waves in a reverb chamber.  A contact microphone picked up those vibrations, sent them back to the recording console, and voilà.  Gotcher reverb right here. [Speaking of plate reverb, the Beatles are said to have made prolific use of that effect while recording at Abbey Road Studios.  So not all of the reverbs you hear on Abbey Road will be from one of those three actual reverb chambers.  Some reverbs on the album may be the real deal (like, say, Loki, God of Mischief, sticking a spear into your back) while others may be an artificially created illusion (like, say, a projected doppelgänger of Loki, God of Mischief, distracting you while the real Loki sticks a spear into your back.)]


         A second important type of mechanical, analog reverb invented in the days before digitization was “spring reverb.”  Like plate reverbs, spring reverbs include both a transducer and a pickup, but they utilize a spring or springs instead of a big metal plate.  As any kid who’s stretched a Slinky knows, a wave induced at one end of a spring will bounce back and forth along the spring’s length, just like a sound wave bouncing back and forth in a tiled room.  The big advantage of spring reverb over plate reverb is size, since a juicy-sounding spring reverb can fit into a much smaller space than a juicy-sounding plate reverb.  The disadvantage is that a spring reverb tends to sound brighter, more artificial, and, well, “springier” than a plate reverb, which tends to sound warmer and more natural.  So while a plate reverb will sound great on vocal recordings, a spring reverb on vocals may sound robotic or alien (which is still great if that’s what you’re going for).  However, as the early music-nerd experimenters discovered, spring reverb almost always sounds tremendous when applied to the sound of an electric guitar.  So manufacturers like Fender Musical Instruments began including spring reverbs in their guitar amplifiers, and gnarly waves of spring reverb began to appear on recordings by artists such as the now-legendary Dick Dale – who, as a result, became the Silver Surfer’s favorite guitar player.

         So, when it came to applying an artificial but great-sounding effect to recorded music, reverb was covered.  But what about echo?  As noted above, you need a room at least 56 feet long to create a natural echo, or a room with 56 feet worth of complicated reflectors and diffractors – and that’s only if you’re happy with a short echo.  Also, you couldn’t reasonably create a useable “plate echo” or “spring echo” unit, because those suckers would be ginormous, like effects units used by God or Galactus.

         Thus the problem of how to apply artificial echo to recordings required the appearance of the most nerdily magnificent of nerdy music nerds, a veritable musical meganerd – indeed, the sound-engineering equivalent of Tony Stark trapped in a small, echoless cave, forced to invent an Iron Man effects unit in order to blast out of imprisonment into the vast, echoing outside world.

         Thankfully, the blossoming music-recording industry of the 1940s and 50s was blessed with just such a Tony-Starklike meganerd, a musician and inventor who is often acknowledged as the single most important innovator in the industry.  His name was Lester William Polsfuss, but he became better known to musical history as Les Paul.

          It’s difficult to separate Les Paul’s invention and use of “tape echo,” or tape delay, from his many other accomplishments as a musician and inventor, since he was doing all of it simultaneously, with each thing he created influencing every other thing.  All of his work combined into a gestalt resulting in tools and techniques that changed how music was recorded from then on.

         However, since this post is “Some Entertaining Bullshit about Echoes Echoes Echoes,” we’re going to focus on just the artificial-echo aspect of Les Paul’s innovations.

         In order to hear complete echoes, not just reverb, Les figured out that he needed both a recording and a playback head on one of the then newfangled reel-to-reel tape machines . . . or perhaps even better, two tape machines linked together, with the same tape running between them.  The recording head would copy his original signal – his guitar, his wife Mary Ford’s vocals, or whatever – and the second head would play it back while the performance was still in progress.  The distance between the recording and playback heads would create a delay from the original signal.  So recording both the original signal and the delayed signal at the same time would result in a final product that included the original signal plus an echo.  And it would be possible to vary the length of the echo depending on the distance between the tape heads and the speed of the tape.

         In other words, unlike natural echo, tape echo didn’t depend on the speed of sound and the distance it traveled in air.  Instead, tape echo depended on the speed of the recording tape and the distance that the tape traveled between the recording and playback heads.  Which didn’t have to be anywhere near 56 feet in order to produce an echo.

         Les built himself a nice big echo unit using that technology, but once he had it all put together, it really had turned into something nice and big, like Bruce Banner turning into the Incredible Hulk.  It was great for Les’s own home studio, or to build in other studios, but it wasn’t exactly portable.  So it didn’t take long for other music-engineering nerds to take Les’s basic idea and make it more compact, using tape loops housed in smaller units to create the same effect.  

         One of the earliest, the EchoSonic, was actually built into a guitar amplifier, just as other manufacturers had built spring reverb into their own amps.  In the case of the EchoSonic, the original guitar signal plus its echo came right out of the amp’s speaker.  The EchoSonic echo wasn’t very long, though – it was in the almost-but-not-quite-reverb neighborhood of around 100 milliseconds.  So its almost immediate repeat became known as a “slapback” echo, and it’s all over the rockabilly recordings of the 1950s.  In fact, Scotty Moore, the electric guitarist in Elvis Presley’s band at Sun Records, loved his EchoSonic so much that you can hear a lead-guitar slapback echo on almost all of Elvis’s early tracks.

         Tape delay soon moved out of the EchoSonic amplifier into self-contained units that could be used with any amp or recorder.  For a number of years thereafter, machines like the EchoPlex (beloved by Led Zeppelin’s Jimmy Page, who was also pretty fond of his Les Paul guitar) and the Roland Space Echo ruled.  But tape could be cantankerous and prone to failure, and it still made for fairly bulky units.  So eventually, smaller and more reliable tape-free delay units emerged, first in the form of so-called “bucket brigade” repeating analog signals, and later in the form of digital delays – which can be virtually limitless in terms of echo times and repeats.

         But the effect itself, a truly good-sounding artificial echo, was achieved back in the 1940s by Les Paul, modern music’s own Iron Man. Not to mention the fact that Les was largely responsible for the invention of the solidbody guitar, overdubbing, looping, and multitrack recording, as well as the creation of Gibson’s enormously successful Les Paul model guitar.  He was an absolute magician.  A sorcerer supreme.

         So maybe he wasn’t Iron Man after all.  Maybe he was Doctor Strange.

         However, the massive info-dumps and other such entertaining bullshit about Les Paul’s other magical innovations will have to wait, since the subject of this post has been bounced from the canyon wall as much as it can stand to be bounced.  I’ve now told you all I know about echoes and reverberation, and have no doubt repeated myself in the process.  (See what I did there?)  

         In other words – I’ve suffered for my art, and now you have, too.

         So for the time being, True Believers, in the immortal words – well, word – of Stan Lee: