Compression Depression

sadmusic

“Research finds MP3s make your music sound more depressing” says the latest bit of breathless reportage to come floating down the audio/science news feeds. In this new ‘post fact’ age, I guess I’m no longer supposed to be surprised by the paucity of actual evidence offered up in support of any particular assertion put forward as scientific ‘research’ but in the interests of actual reality, let’s focus the Hummadruz lens on this affair.

As usual, nearly every mention of this that I saw completely uncritically regurgitated copy that looked like it came from one source. I couldn’t narrow it down to a first instance, but the coverage from NME was typical:

New research has found that listening to music in low-quality digital formats can dampened its emotional impact.

According to a study by the Audio Engineering Library, MP3s can have a distinct effect on the “timbral and emotional characteristics” of the instruments involved.

Researchers compared responses to compressed and uncompressed music over ten emotional categories at several bit rates.

It’s always instructive to find out who is responsible for research, so my obvious first action when I read the above quote was to click on that link to the ‘Audio Engineering Library’ and find out who those dudes actually are. Puzzlingly, the link just leads to the abstract of the actual paper, which makes no mention of that organisation.

In fact, searching the web for the ‘Audio Engineering Library’ reveals that there is no such entity, and, instructively, pretty much every search result leads to some variation or other of the story about ‘How compression makes your music depressing’. It’s a veritable self-referential maelstrom. Audio Engineering Library? Someone just made that shit up.*

If ever there was an indication that we are about to enter the land of hogwash and horsepiss, here we have it.

Still, we have the paper right? Published on Researchgate – the science industry equivalent of LinkedIn – to be sure, but proper science will out!

The first thing we should note is that this research is a one-off  publication, on an online site, of a conference presentation. The research it entails has neither been replicated, nor peer-reviewed. This is, in scientific terms, not much more than a bunch of opinions.

We don’t have to delve far into the paper to find its true worth:

3.2 ListeningTest

We used eight sustained instrument sounds: bassoon (bs), clarinet (cl), flute (fl), horn (hn), oboe (ob), saxophone (sx), trumpet (tp), and violin (vn).

Whoa there cowboy! I was told by NME that the compression made my music more depressing. You do know what music is, don’t you NME? What it is not, is a bunch of fixed-note sustained instrument noises taken entirely out of musical context.

In addition to that complete clanger, there is no mention anywhere in the paper about how many subjects were used in these tests, nor anything about how they were conducted – just a lot of technical hocus-pocus about compression methods, and some graphs that are totally meaningless given what we just read. Wading further through this procedural mess, we find so much experimenter subjectivity stirred into the mix that the study is rendered all but useless as a piece of viable science.

To sum up, an unpublished, un peer-reviewed paper, conducted by a fictional institution,  tells us that in an un-replicated study, an unspecified number of listeners (keeping in mind that could be as few as two) were played compressed timbral instrumental single tones (not music) and asked to subjectively choose – from a list pre-determined by the researchers – how those noises made them feel.

Would you conclude that from there you could get to “Research finds MP3s make your music sound more depressing”?

No, me neither.


*Addendum: It seems they probably mean the AES (Audio Engineering Society) Library, where the paper is also archived. So let’s chalk that one up to sloppy journalism, rather than wilful deception. On the AES site, the presentation appears under its actual title The Effects of MP3 Compression on Perceived Emotional Characteristics in Musical Instruments [my emphasis].

Notice that this doesn’t make any claims about music, per se, and is a much more accurate appraisal of what the study was actually looking at (see comments below for further clarification).

Mercurial

freddie

“Science Confirms That Freddie Mercury Was Basically The Most Amazing Singer Of All Time” screams one headline. “Freddie Mercury Is The Greatest Singer Of All Time, Because Science Said So” says another. “Queen’s Freddie Mercury Had One Of The Best Singing Voices Of All Time, According To Science” gushes a third. I’m sure you saw them in your social media feed in the last week or so.

So what’s the story then? Have scientists come up with some amazing new method for applying empirical assessment to artistic subjectivity? Has scientific endeavour somehow managed to ‘confirm’ that Freddie Mercury is indisputably the most accomplished singer in human history?

Well, as you might have guessed, not so much.

Let me say from the outset that, by a considerable agreement of subjective reckonings, Mercury is an amazing singer. His vocal prowess is all the more extraordinary in light of his lack of formal training; he was self taught instrumentally and vocally, and claimed not to be able to read music. We really don’t need science to be able to legitimise his talent, per se.

And indeed science is not even attempting to do any such thing. The hyperbole above is generated by the lamest corners of the social media press, after the recent publishing of a paper by Christian T. Herbst et al, from the Faculty of Science at Palacký University, Olomouc, in the Czech Republic. Herbst frames the intentions of the research like this:

“The purpose of this study was to conduct a viable analysis of publicly available data material, in order to arrive at more empirically based insights into Freddie Mercury’s voice production and singing style.”

So the researchers, who self-describe their work as ‘fan science’, take it as a given that Freddie is an awesome singer and are simply gathering some data to help understand – in a technical way – how he did his stuff.

To do so, they examined both his speaking and his singing voice, concentrating on its timbral qualities, vocal range, vibrato and vocal subharmonics. In addition, they had a trained singer emulate some of Mercury’s vocal stylings and observed the active vocal cords with an endoscope. It is all fairly fascinating in its own right, and the breathless exaggeration from some sections of the interwebs really does the science no favours.

So what do the results of their efforts tell us? Well, not a lot that an experienced singing teacher couldn’t have concluded just by listening, in all honesty. They found that Freddie’s vocal style encompasses a remarkable variety of techniques, including a faster than average vibrato, the occasional use of vocal subharmonics (mostly to add a growl or burr to his voice) a proficient control of phonation and an impressive vocal range (although not quite the four octaves often claimed).

The paper provides empirical details of all these things, although, surprisingly in my opinion,  not much investigation into Mercury’s falsetto, which was one of his most dramatic vocal accomplishments (Mercury showed an almost incomparable ability to elide from his upper vocal register into falsetto and back again with virtually no audible transition – singers will tell you that this is very difficult to do).*

So to sum up, we already knew that Freddie Mercury was a pretty astonishing singer. What this investigation does is shed a little bit of scientific light on how he did his thing. What it does not do is ‘prove’ anything about his standing in the dominion of wonderful singers through the ages. And truly, that task is simply not the concern of science.

You can read the full technical paper ‘Freddie Mercury—acoustic analysis of speaking fundamental frequency, vibrato, and subharmonics’ here.

 


*You can hear many examples of this in the early Queen albums Queen, Queen II and Sheer Heart Attack. It is notable on the songs Lily of the Valley, Nevermore and The March of the Black Queen. Mercury’s use of the technique diminished as the band became more conventionally ‘rock’ oriented in later years.

Brainless

Over the last few months I’ve had numerous articles pop up in my Facebook news feed of the kind that promise to reveal some new ‘scientific’ discovery or other that will just amaze the socks off me. One of the favourites – going by the number of times I’ve seen it shared – is this one:

“According to Scientists, This is The Most Relaxing Tune Ever Recorded”

The one page sound-bite rich story is widely dispersed over numerous ‘health and wellbeing’ type websites (like this one), where it is for the most part uncritically accepted as a proper piece of news. It outlines the results of ‘a study’ that has honed in on the single most relaxing piece of recorded music ever to have graced human ears. I know – quite a bold claim – but it’s science, my friends, so you couldn’t just pull that kind of thing out of your ass, right?

The ‘tune’ in question turns out to be a piece called Weightless by ambient music trio Marconi Union. You should probably listen to a little bit of it before we go on – I hope it won’t relax you so much that you can’t come back after the break.

Well. Cute idea for a video, but in my considerable experience of the genre, that’s fairly generic electronic ambience.

According to the ‘news’ article:

This eight minute song is a beautiful combination of arranged harmonies, rhythms and bass lines and thus helps to slow the heart rate, reduce blood pressure and lower levels of the stress…

…and

The results showed that the song Weightless was 11 per cent more relaxing than any other song and even caused drowsiness among women in the lab.

The more you read, of course, the more you begin to see the divergence between the hyperbolic claims of the headline and the actual content of the piece. “11 percent more relaxing than any other song”? What does that even mean? 11 percent more relaxing? Calibrated how? Any other song ever written? Any other song of the same genre? Or just any other song on the iPod of one of the ‘women in the lab’ (is it just me, or is the implication here that the men in the lab were far too macho to be influenced by the wafty charms of the New Age ditty?).

Oh, here we go:

this song induced the greatest relaxation, higher than any other music tested till date

Right. So that would be how many songs, exactly? Not all the tunes ‘ever recorded’ is my guess.

Having worked for many years writing music for advertising, I can easily spot a marketing campaign when I smell one, and this one veritably reeks of fish. But a marketing campaign for what, exactly? There’s no product mentioned in the article, and it doesn’t seem like a promotion for the band. But I guess that’s possible. Let’s see what the internet has to say about Marconi Union.

OK, not much to be gleaned out of the obviously self-penned Wikipedia entry, other than that Marconi Union uses the flimsiest of pretexts to contrive to have their name linked with that of ambient music guru Brian Eno (in several different ways).

What about the ‘scientists’ involved in this astounding breakthrough? The experiment (we’ll call it that for expediency’s sake) was run by an entity by the name of Mindlab International who describe themselves as  a ‘neuro’ marketing company. Their website is slick and snappy.

But here’s one thing I’ll tell you about marketing – it’s not science. The sole goal of any marketing company on the planet is to gather enough data to convincingly support exactly what their client already believes to be true, extracting a generous fee in the process. Not convinced? Consider this: the marketing company is hired by the product maker. The product maker already thinks their product is the best thing since sliced bread. The marketing company who tells their client otherwise is therefore wrong, and gets fired. Marketing companies are the definition of the messenger who really doesn’t want to be shot. So, being a successful marketing company is all about finding convincing ways to make the message appealing to the client. If you can also convince them that you had a hand in increasing sales, that’s a bonus, but don’t think for even a second that that’s their raison d’être (notwithstanding the fact that many of them apparently believe that it is).

In case it needs to be said, none of this is the job of science. Science is about determining truth, no matter what the consequences to human sensibilities or dog food sales. Good science is out of a job when it comes to the advertising business.

The fact that this story involves a marketing company and a bunch of exaggerated claims  immediately raises red flags. It’s quite obviously not concerned with giving the reader factual news. No,  it’s solely about selling something. The more observant among you will have noticed that the video of Marconi Union’s Weightless – linked in the article (and above) – is interestingly named. It has the peculiar bracketed codicil ‘Radox’ in the title.*

Ah, yes. It’s all starting to make sense. So factoring ‘Radox’ into a search with ‘Marconi Union’ and ‘Mindlab International’ gets us straight to the nitty gritty. The first sentence on this page at a site called musicactivation.com reads:

Radox Spa brand has made an ambient track that is scientifically proven to be more relaxing than a massage.

Oh, now what a coincidence! The ambient track Weightless, which was made by (I think we can assume ‘commissioned by’) Radox Spa bath salts just turns out to be ‘the most relaxing tune ever recorded’.

Are you smelling any science here, sports fans? Or are you getting an overpowering aroma of horseshit? For the full experience, you might like to watch this:

Well, that was the biggest load of bollocks I’ve seen in a long while. I wonder how many completely unscientific instances of prestidigitation you caught there? If you needed proof that Mindlab International is entirely unconcerned with actual science, there’s plenty of ducking & weaving going in that clip.

What’s happened with this whole thing is that hundreds of websites have mindlessly snapped up a piece of marketing propaganda (something that was, no doubt, fed out to the media machine as a press release from Mindlab International) and completely credulously echoed it far and wide across the social networks as if it actually had meaning. I probably don’t need to rephrase it to reflect actuality, but for amusement’s sake, this is how that headline should really have read:

“According to a Marketing Company, a Piece of Music that their Bath Salts Client Commissioned is the Most Relaxing Tune Ever Recorded”  

Not something that’s going to rapidly circulate on the social media, is my guess.


*Update: since I penned this piece, Marconi Union seem to have disassociated themselves from Radox, so the original video I linked here has disappeared. References to Radox don’t appear on the re-uploaded version of Weightless

The Sound of Distant Drumming…

bilbo

With Peter Jackson’s movie version of The Hobbit killing box offices around the world, most people can hardly have failed to notice that, like Spielberg and Lucas before him, Jackson is using his considerable clout to spearhead another leap in technical quality for the cinema experience. I am talking, of course, about The Hobbit‘s release at the projection speed of 48 frames per second, which has already become popularly known by its acronym, HFR (high frame rate).

Jackon’s decision to use HFR for the film was almost certainly prompted by the desire to increase the quality of 3D – something which it indisputably does. Unfortunately, HFR got off to a bad start when news got out that audiences at the CinemaCon preview of The Hobbit in April of 2012, were finding the high resolution experience rather disconcerting. Mostly, the criticisms centred on the HFR looking ‘stagey’ or ‘fake’ or ‘cheap’. Peter Jackson brushed off the criticisms, saying we’d all get used to it, but there is no question that HFR has some ‘issues’. Since the release of the full movie, there have been many dissections of the curious nature of the 48fps effect in the film, some smart and some fairly far-fetched. I have my own hypothesis as to why we have trouble with the HFR experience, but I mostly want to talk about one aspect of that here. And it’s an aspect that no-one seems to have picked up on yet: the sound.

It’s not really that surprising to me, I have to say, that no-one has thought to scrutinize the part that sound plays in the perception problems for a high frame rate experience. People hardly pay attention to sound at the best of times, and in this particular case the whole issue has been entirely one of ‘the look’. A movie, however, is not all about what you see.

For you to follow my argument in this post, I need to just give a brief overview of the usual experience of sound in the cinema. Currently, most movies you see are delivered to an audience in a format that was first formulated in the 1970s by Dolby Laboratories and then widely adopted in the 1990s for the cinema. It is called 5.1 surround sound (some high end modern movies use a variation of 5.1 called 7.1, but for purposes of this discussion it’s essentially the same thing). 5.1 is arranged in such a way that three speakers across the screen deliver most of the critical sound. These are designated as Left, Center and Right. Usually these speakers are placed just behind the screen, along a horizontal center line halfway down. Two further speaker groups (they are usually groups, but just think of them as single channels, because that’s how they are treated) are designated Left Surround, and Right Surround. These are placed to the side and behind the audience. This array, the L,C,R,Ls,Rs is the ‘5’ of the 5.1, referred to in the profession as ‘5.0’. The ‘.1’ is the Low Frequency Extension, or LFE, which is situated behind the screen with the LCRs, usually on the floor. The important thing about the 5.0 array is that this is what determines the spatial placement of sounds for the audience.

soundlayout

Over the last couple of decades, the surround sound array has proved to be a versatile and durable system, providing considerable enhancement of the 2D experience. Here’s the thing to keep in mind, though: the key to the effectiveness of the whole notion of surround is that the sound can be made to appear to be – fairly convincingly – anywhere inside the theatre in front of the screen. The whole surround sound concept is based on the idea of enveloping the audience.*

The increasingly fashionable use of 3D over the last five or six years has, however, introduced something new into the movie experience: depth. 3D imaging is, in a way, the complete obverse of surround sound. 3D doesn’t bring the image out into the theatre as much as it expands the depth behind the screen into which the viewer looks. This creates an obvious problem for sound: how do you make the sound feel like it’s back there with the image?

If an object – let’s say a racing car – is on a flat screen (in 2D), then no matter where it is on that screen, it’s always on the same plane as the the speakers reproducing its sound. If  the car appears to be receding into the distance, we have learned by cinema sound ‘convention’ that its sound will get quieter (fade away) to make it seem like it’s attached to the car, but in realistic terms it simply can’t appear to be coming from a point source a  hundred meters beyond the screen (it’s crucial to understand here that our ears don’t judge the location of a sound solely by its loudness. In addition to loudness, we detect small differences in delay times to place an object aurally in space, as well as as different kinds of reverberation textures and times, and comparisons to other sounds we might be hearing. Our brain’s processing of audio information is complex and detailed, and artificial sound reproduction has pretty much always been a kind of ‘cheat’). As it happens, it’s perfectly acceptable in 2D because the image of the racing car and its sound never actually go off that 2D projection plane.

In 3D in the movies, though, our brains are forced to deal with a kind of cognitive dissonance. The racing car appears to be much more realistically moving at some distance away from us, but we hear the sound that it’s making on the same screen plane as every other sound we’re hearing! In fact, the 3D ‘world’ space and the domain of surround sound hardly overlap at all.

3dcover

This odd paradox is a legacy of the stumbling technical evolution of the cinema. The whole point of introducing surround sound into the movie environment was to attempt to create another level of involvement for the audience. Because the image on the screen was flat, no-one really thought of having the sound go beyond the screen; like the wall of the cinema to which it was attached, the screen plane has always been treated as a hard and absolute boundary (aside from anything else, there would be the technical and economic consideration of having speakers – and a whole room – on the other side of the screen). The difference between 5.1 and everything since old fashioned mono, was that surround was largely about pulling the sound forward and off the screen, by creating the ambiences of things that you did not see.

With 3D, a whole new space opened up – a space full of things we can see and that can be anywhere from slightly in front of the screen plane to an infinite distance away. And if those things make sounds, then our brains quite understandably expect those sounds to be glued to their matching apparent position in space.

This was never a problem in 2D, because 2D is a stylized way of looking at the world which we have learned to accept as ‘reality’ through massive exposure to 2D images over more than a century, and to which we have become habituated. Up until The Hobbit came along, there wasn’t even much of a problem with 3D, because the quality of 24fps 3D is not really that great and you just didn’t notice the ‘gluing’ error that much. But with the extraordinary detail that is available in HFR, the 3D begins to push a level of resolution that approaches reality. And, as that happens, our brains start to tell us that something is out of whack: “That horse galloping off into the distance! It’s very quiet, but its sound is coming from right in front of us!”

Not that we process it consciously, of course, but it adds to the sum feeling that there is something kind of wrong with what we’re experiencing.

While I was watching The Hobbit this strange dissociation of sound and image kept catching me at every turn: Bilbo runs behind a rock but his footsteps are unattached from him; an arrow hits a distant ledge in a cave and it sounds like a small stick being thwacked next to my ear; a warg runs off into the distance and its growling doesn’t manage to go with it. In general, the whole soundtrack is somehow ‘smeared’ and its details diffuse. Now, I know the guys who did the sound on this film, and I can tell you – they really know their stuff. And I’m willing to bet that when I get to view The Hobbit in 2D here in my studio in 5.1 on BluRay, it will sound spectacular. I believe that the problem is not with the way the sound is done, but with the way the sound is done for an HFR 3D film. The sound for The Hobbit has been created in the manner in which we normally create sound for the surround cinema environment and that process is now approaching a point where it’s simply not adequate to create an illusion of reality.

This difficulty is not confined to the sound alone. In The Hobbit, a similar predicament exists with the lighting and other aspects of its cinematic ‘world’. We’re at a stage with this technology where the whole technical way we make films needs to be rethought.

For sound, I don’t really know how we can easily remedy this situation. One of the other technical innovations that was rolled out for The Hobbit was a new sound format by Dolby Labs called ‘Atmos’ (which unfortunately I didn’t have  a chance to experience, since there are no cinemas in the southern hemisphere – other than the Embassy in Jackson’s home town of Wellington, NZ – equipped with it). Dolby understands that as cinema image resolution increases, the 5.1 (or 7.1) array will start to struggle to hold its ground. The Atmos system is an effort to expand the level of detail of, and control over, the aural environment. Atmos employs a speaker array with an astounding 64 programmable point sources throughout the theatre – that’s 58 more speakers than 5.1 – but I’m sure you’re ahead of me here: this hasn’t changed the overall concept of cinema sound. The sound is still inside the auditorium, not back where the 3D is happening. It is likely that Atmos will give a new level of detail to what you hear in the theatre, but it still needs to somehow address the sound on the other side of the artifical boundary that is the screen plane.

Of course, there is a way to tangle with this puzzle, but as I said, it’s not likely to be easy. Or cheap. It involves computers, and sound modelling and other kinds of new tech. It’s rather too complicated to go into at the end of this long post, but maybe I’ll attack it at another time.

_____________________________________________________________________________________________________________

*Director John Boorman, an outspoken critic of surround sound, bemoaned the fact that he’d spent his whole career attempting to get his audience involved in what was happening on that flat screen and now he was expected to embrace a technology that was trying to pull them out of it.

One Trick Pono

The ‘big’ news in audio this week is that legendary musician Neil Young has introduced a new music player to the world – the Pono. The word ‘pono’, apparently, is Hawaiian for ‘righteous’. The principal selling point of Pono is, according to Mr Young, that it presents the listener with ‘the best quality audio available’. Here he is pitching the concept (badly) to a fairly underwhelmed David Letterman:

Flea, bassist from the Red Hot Chili Peppers, effusively spruiked the Pono experience to Rolling Stone:

“It’s not like some vague thing that you need dogs’ ears to hear. It’s a drastic difference.”

Rolling Stone reports that Flea discerned this ‘drastic difference’ after hearing Aretha Franklin’s ‘Respect’ played in Mr Young’s car. Now, I suppose Neil Young has a pretty good sound system in his Cadillac, but trust me, a car is not an optimal listening environment for a phone conversation, let alone for judging music quality, so I for one am taking the audio assessment of a bass player from a rock band criticized for the egregious loudness of its recordings with a grain of scoff.

See, the problem with this kind of thing is one of perspective. Even if we accept that Pono will deliver an appreciable difference in fidelity to what is already available – and for the record, I don’t – Neil Young thinks enough people care about that to make his idea a commercial viability. He obviously doesn’t go to cinemas, have teenage daughters, listen to the radio, or pay attention in any way to how the great majority of people consume music. He’s failed comprehensively to understand the reason that compression codecs like mp3 caught on in the first place, and, worst of all, he’s possibly the only person in the world not to have learned a business lesson from the VHS/Betamax format war of the late 1970s (which, in case the point needs to be made, showed that people don’t give a flying fuck about quality when it comes down to it). As much as I admire Neil Young as a musician, I think his business acumen sucks.

Let me put it to you from my personal perspective as a prospective Pono punter: I’m a trained sound professional with a love of music – new and old – and an appreciation for the amount of work that goes into the craft of getting it to my ears. I love good quality sound. Occasionally I buy music for the fidelity of its recording. But mostly, I don’t. Mostly I buy it for its content. I buy it for the songs, or to play while I’m making dinner, or to listen to in my car when I want to be able to ignore the hum of the city. I rarely have the time to sit and just listen to a recording in the relatively superior listening environment of my sound studio. I like to take my music with me, so I have some on my phone, and some on an iPod in my car. I have re-purchased music I already owned so I can do this, and have also digitized my not-insubstantial CD collection. Now – WHY ON EARTH WOULD I BUY A PONO AND ALL MY MUSIC AGAIN? I know that, theoretically, mp3 and AAC are inferior to uncompressed digital (whether that extends to the stratospheric192kHz/24-bit sound that Pono offers is arguable…) but I don’t care. I bet the Pono music won’t be as cheap as the iTunes store, and I bet the Pono won’t interface with my car. And I already carry around music on my phone – why would I want another gadget cluttering my pocket? It’s one of the cool things about the iPhone: I have music, a phone, a diary and a camera with me at all times in one unit. What I’m trying to show you here is the vast hurdle that Neil Young is proposing to leap, on the basis that people care about superior sound quality.

An interesting aspect of the reporting of this story is that the press seems to have picked it up under variations of this leader: “Neil Young Expands Pono Digital-to-Analog Music Service”, which, aside from being an entirely inaccurate appraisal of the way the gadget works, rides on the coattails of the hoary old myth that analog recording is somehow magically ‘superior’ to digital. Analog is different to digital. That is all. You may even prefer the sound of old analog recordings over modern digital ones, but that has, these days, nothing at all to do with tehnical quality. It’s merely fashion. And it’s a fashion that can, in fact, be reproduced adequately – for the great majority of listeners – under existing digital audio codecs. Why, if you really want very high quality audio, it’s already available in iTunes (not quite the 192kHz offered by Pono, but Jesus, people – Aretha Franklin IN A CAR???)

My prediction? One year on from the official launch of Pono and you’ll be buying the things on eBay for 50c. Come back and tell me I was wrong.

Fish or Foul or Fantasy?

As promised in the last post, today I’m putting forward my three best hypotheses for a solution to the mystery behind the West Seattle Hum. They’re ranked in what I consider the most likely order of plausibility, from least to most

Disclaimer: I see some people from Seattle are visiting. I should make it clear that I live in Australia and my speculations on this matter are based on my readings of the West Seattle blogs & forums, on researching of map data and tide and astronomical tables, and on my expertise as a professional sound worker. I have tried to be as accurate as I can, but am open to any corrections of errors or omissions that I may have made.

The Cause of the Hum: Speculation #1

The map I made in the last post throws up one element that might give us a clue to what’s going on with the Hum: some indication for direction of the origin of the sound. A direction, if it can be established, would indicate a point source that could be tracked down. The directional information on my map, slight as it might be, indicates a source position which would tally closely with the location of the Lafarge gypsum works & shipping yards on the Duwamish river, which was suggested by numerous commenters as a likely candidate for the Hum. It is extremely possible that some piece of machinery – a fan, an air conditioner or an electrical transformer perhaps – could make a noise like that recorded by Julie Schickling. According to the West Seattle blog, when Lafarge was approached about the sound, a representative from the company didn’t dismiss out of hand the idea that the Hum might be coming from them, but said also that they had no idea what it might be. It seems to me that a loud point source would be reasonably easy to locate though, and at least one commenter who followed this line of enquiry seems certain that the Lafarge plant is the culprit:

‘We finally were fed up with the infernal noise and went out to look for it. From Highpoint to Highland Park to South Seattle Community College to Pigeon Point and then finally West Marginal. The noise is clearly coming from the Lafarge Cement plant.’ ~ said R0b0, on the forums

But another resident, on attempting to track it down noted that the noise diminished as she approached the plant and seemed instead louder downriver to the South:

‘We did drive down a couple of nights ago to try and find it and we thought it might be coming from a ship that was moored off the Northland pier on the Duwamish…. We did drive further north toward the cement plant, but it seemed quieter there.’ ~ said Kay K

A few commenters on the West Seattle blog and the forums suggest they will make a video of the Lafarge plant to demonstrate their convictions, but so far no such video corroboration has materialized. Since this would seem to be an extremely easy thing to accomplish given the proliferation of phones & cameras with video capability, the absence of any such evidence (which one would think might be quite unequivocal) is puzzling.

If the Hum is a mechanically generated sound, though, the biggest question is how it might be heard right across West Seattle without the point source being deafening. And not just heard, but heard loudly in places as far away as Lincoln Park. Radiated sound, under normal circumstance, is a pretty straightforward thing. Soundwave radiation follows the Inverse Square Law, which says that the intensity of a sound is inversely proportional to the square of the distance from the source. Using this law we can quite easily calculate how loud a sound would be at Lincoln Park if generated at Lafarge. If we assume that the original sound is 115 decibels, which is VERY loud (around the kind of level you might experience at a loud rock concert) then by the time it traverses the 4.5k (3 miles) to Lincoln park, it has decreased to 42 decibels. That’s really quiet – somewhere between a subdued conversation and a whisper. That’s also assuming that there’s nothing in the way – that is, there would need to be a direct line of site between Lincoln Park and the Lafarge plant to get that even that meagre level of sound. I can tell easily from looking at the Google terrain map that this is not the case. I think I could confidently say that under normal circumstances, a resident in Lincoln Park could not hear sounds emanating from the Lafarge area. To add to the problem, for people living closer to Lafarge, there would be no question whatsoever about the location of a noise of 115db (just like you would know without a shadow of a doubt if there was a rock concert happening at the end of your street).

As bad as this looks for the hypothesis that the sound comes from the cement works, there is in fact an explanation that might come some way towards creating a plausible mechanism that could carry the sound across West Seattle.

If the conditions over the area are such that, on the mild, clear nights, an inversion layer forms, it is entirely possible that sound travelling up from somewhere in the direction of the Lafarge plant could be reflected back down into the suburbs. Inversion layers are much more likely to form in the early hours of the morning as the surface temperature cools, so this would suggest the Hum should be heard well after midnight – probably around 2 – 4am. This does fit with many of the reports on the West Seattle blog. Obscure kinds of atmospheric effects could also be at work, amplifying the sound in odd and uneven ways across the district.

This scenario would further help to explain the diffuse, directionless nature of the sound and you could also reasonably expect similar kinds of phasing and beating effects to Ms Schickling’s recording. Additionally, it would be in keeping with the drifting in volume effects noticeable on that recording.

But I reiterate – this explanation requires a substantially loud point source which would not be that difficult to locate with a decibel meter and and even mildly determined effort.

The Cause of the Hum: Speculation #2

In the NPR story that I mentioned last post, Dr. Andy Bass, from Cornell University, tells listeners that when Midshipman fish are mating:

Individual males build a territory, if you will, under a rock shelter. And from that rocky shelter, they produce that hum advertisement call to attract females to their nest.

In the YouTube video in the last post, that behaviour is clearly observable: the fish is taking a position in a hollow under a ledge and making its noise. From an acoustic point of view there is a compelling reason it might want to do this – a small cave under a rock would provide a kind of resonant cavity with a soundboard, helping to amplify its calls. Now, I’m certainly not an expert on the Midshipman fish, but let’s suppose that, like insects or frogs, the individual that makes the loudest sound has the best chance of attracting a mate. We would, therefore, have a situation driven by evolution where the Midshipman fish actively seeks out places that help amplify its sound. And each generation would tend to favour the fish that gets louder. So what we would have is a two kinds of evolutionary pressure at work – one on the fish’s physiology, and the other -significantly I think – on its behaviour. In the natural world, this is going to be a kind of self-regulating mechanism, since a fish only needs to be louder than the next loudest fish and no more – it’s a balance between loudness and energy expenditure and locating the most effective rock ledge available. Around Seattle, though, the fish has extra competition: boats, ferries, industrial racket – all possibly creating sounds of a similar nature to its own mating call. So a Midshipman fish quite conceivably faces an evolutionary imperative to outcompete human-made sounds in addition to the calls of other Midshipman fish.

If this is the case – and I think it’s a supposition on par with the same phenomenon being recorded with birds – then humans may have provided a problem for the Midshipman fish around West Seattle. As luck would have it, though, I think humans may have also been the engineers of a solution to the fish’s problem, and the creators of a new one of their own.

I have only been to Seattle once, in transit, so I can’t say I’m familiar with the city at all. But right now I’d just love to go to the Lafarge container dock on the Duwamish and take a look at it. I’m betting that underneath those big landings that flank the river, are hundreds of  nooks and crannies with cavities and sounding boards – Midshipman fish heaven. Better than rock, they’d be roofed with wood and concrete and metal, materials that resonate in an excellent fashion, given favourable frequencies.

I want to remind you of a few of comments I featured from the West Seattle blog in the previous post:

‘I’m familiar with this noise too and think it is coming from the sewers. Next time you hear it go to a storm drain and see if it is louder’ ~ said mmd.

‘What’s weird is it sounds loud inside and when you walk out it seems quieter’ ~ said DRW 

‘Reminds me of a didgeridoo…’ ~ said steph

‘Seems to change pitch/intensity in a slow rolling pattern, makes me wonder if we’re hearing an interference pattern between multiple sources.’ ~ said ben

When I listen to the recording made by Julie Schickling and compare it to dry recordings of the Midshipman made by Cornell University, I can hear immediately that there are (at least) five distinct audio phenomena at work in Ms Schickling’s recording that differentiate it from the latter. Phasing, resonance, ‘beating’ and reverberation, and a distinct swelling and abating of the sound, which is probably an effect of changing air pressure, or breeze direction. The first four of these can be commonly found in one circumstance: inside a tube or other long resonating cavity. It’s exactly the kind of effect you get when you play a didgeridoo, for example: the initial sound vibration interacts with itself to resonate, phase and create harmonics.

Now I’m not suggesting that the Midshipman fish has evolved to the point where it can play the didgeridoo, but are there other tube-like cavities to which it might have access? Long cement tunnels filled with air, say?  Like… stormwater drains?

This, then, is what I consider the next most plausible hypothesis for the West Seattle Hum: as the weather warms up coming into Spring, the male Midshipman fish starts seeking out habitat suitable for its mating rituals, around the coast of West Seattle and especially right down along the Duwamish river near the Lafarge container docks. What it’s looking for are large cavities with exceptional resonant properties. These could be concrete piers, metal boat hulls, wooden wharves or even culverts and drains on the river frontage. I’m betting that there are numerous stormwater outlets that go down to the Duwamish, and probably others on the Western coast as well. These possibly even run submerged into the water. The stormwater drains undoubtedly reach everywhere back up underneath the suburbs of West Seattle. When the fishes start producing their mating call, the vibrations from the resonant cavities in the river and near the drains, begin to generate sympathetic resonances in the air columns in the stormwater tunnels, amplifying the sound, but also very importantly, carrying it up under the streets, where it echoes out from any opening to the outside. It would be formless and directionless – seeming to come from everywhere at once, even, perhaps, being louder inside a house than out. Because it’s being channeled in the drains, in some areas you might hear it clearly and loudly, while in others – even quite close by, you might not hear it at all. The sound being pushed through multiple tubes and tunnels would surely phase with itself and reverberate, and surge as the air pressure changed, reacting with itself to create harmonics such as we hear in Julie Schickling’s recording. The sheer amplification potential of this massive resonant chamber under West Seattle would spur all the fish in the area into competition, rather than exciting just a few proximate neighbours, as would happen in a completely natural environment. As anyone who has recorded frogs or insects knows very well, these creatures in competition can achieve almost deafening levels of sound. It is, in my view, entirely feasible that something like this could be happening in this human-altered Midshipman fish environment.

I want to point out here another factor which may be in play and hasn’t been noted elsewhere: The Labor Day weekend this year, when most of the recent incidences of the Hum were noted, just happened to coincide exactly with a full moon (full moon Aug 31, 99% Sept 1, 98% Sept 2, 94% Sept 3). I can’t say if it’s true of the Midshipman (biologists?) but I do know that the full moon spurs on the mating cycles of many sea creatures. Seattle is also currently experiencing a period of unusually extended dry weather, so the nights over the time of the reportings were clear and mild and the moon would have been prominent in the night sky. Maybe over the Labor Day holiday there was a veritable Midshipman fish orgy going on.

‘I’ve been in Sunrise Heights for 50 years and just started hearing this a couple of years ago. I can tell you that I hear it almost monthly, toward the last weekend of the month’ ~ said LisaH, on the forums.

Or just maybe, Lisa, on every full moon…

The best thing about the Midshipman proposition is that it is trivially easy to test. Next time the sound starts up, someone just needs to go down into the drains. I should think it would be immediately obvious if the sound is coming from there. It would be way louder than anywhere on the streets.

I think also that there are some predictions that can be made if it is the Midshipman fish, and if it is coming from the stormwater system:

1: It’s unlikely the sound will be heard when it’s very windy, from any direction: wind will tend to interfere too much with the air pressure to allow resonance to form well. Mild to warm still conditions would work best.

2: It’s unlikely the sound will be heard through the colder months: the fish don’t make the noise unless mating. You’d certainly never hear it in Winter.

3: It’s unlikely the sound will be anywhere near as prominent during the day, even on quiet early mornings: the fish mate at night.

4: The next clear night with a full moon would be the time to go out with a recorder and get your evidence.

The Cause of the Hum: Speculation #3

My third, and final, speculation on the cause of the West Seattle Hum will, I anticipate, be the least popular of all three among the district’s residents, but I believe it is the most plausible of all. ‘Less popular than the fish!??’ I hear you cry. Well, yes. Speculation #3 is that there is no Hum. Well, at least, there is no one thing that’s causing ‘the’ Hum.

When you have a lifelong interest in weird shit, as I do, you get quite familiar with certain kinds of phenomena that occur time and time again in slightly different guises. One of these recurring phenomena is filed under the heading ‘Mass Delusions & Hysterias’. Now this is not to imply that the residents of West Seattle are somehow mad, or even that people who have heard something are imagining it. But reading the comments on the West Seattle blog, you do feel, as I said at the start of my story in the last post, that all these folks may not be describing exactly the same thing. Some, for example, say the Hum is low pitched – that’s not how I would describe the recording made by Julie Schickling (which other commenters say is exactly the sound they have heard). Some describe the Hum as ‘a grinding sound’, while others say it’s like tinnitus. Some describe it like the sound of trains, others say it’s a noise like ferries, and yet others, helicopters, vacuum cleaners, and idling cars. These are all very different sounds.

Further, the researchers from Washington University, who proffered the Midshipman fish explanation, have not been able to establish their hypothesis as plausible mechanism after attempting to get a sound recording of it (although I do feel I must point out that one failed recording expedition is not any kind of proof that there are no Midshipman fish in the Duwamish or off the coast of Seattle at this time – it  only demonstrates that there was no Hum on the single night that they made their recordings).

Then we have this rather… perplexing… situation as reported by the Seattle Times:

The [West Seattle] blog’s Patrick Sand said the sound was active for two or three days but stopped after people wrote about it. “That seems to have scared off the noise,” he said.

Whoa! Hang on a second there. So, people heard the sound in spades over the Labor Day weekend, but it suddenly disappeared entirely when under scrutiny? That, my friends, is a major red flag in favour of the mass delusion phenomenon.

In essence, it works like this: it’s a holiday weekend, nice weather. People are possibly out & about a bit more, staying up later than usual. In the early hours, some irritating humming noise starts up – it’s a street sweeper, but you’ve not really been awake at this hour much before and never heard one, so you can’t place the sound. Next day you mention it to a friend. ‘Isn’t that the damn Hum people were talking about back in ’09?’ asks your pal. Maybe it is, you think, and tell someone else over coffee. ‘Oh, I heard that last night!’ says your co-worker, who is actually talking about the transformer in the substation at the end of the street, which they’d not really noticed until now. Then you log on to the West Seattle blog and ask if anyone else has heard ‘The Hum’. Before too long, lots of people recollect that, yes, maybe they heard it too…

If you haven’t already, go to the blog now and read down the comments from the beginning with that thought in mind. You’ll keep tripping over observations like these:

‘I think it may be the power of suggestion. Now in Upper Fauntleroy, with a window open to the east-facing back yard, I’m thinking I hear something ambient out there.’ ~ said WSB on the forums.

‘This is not the same hum I’ve noticed in the past.The old hum seemed to be during daylight hours and seemed to come in from the West.’ ~ said old timer

‘This is incredibly weird, because I live at the top of Highland Park Way, and so you’d think based on the description and direction I’d hear it louder than anyone. But I don’t. I have no idea what you all are talking about. Don’t get me wrong, I have no doubt there’s SOMETHING, but I’ve NEVER heard it.’ ~ said datamuse

‘Now I can’t sleep because I keep wondering if I’m going to hear this annoying & unusual sound tonight! I think I’ve heard it once before…’ ~ said EJ

…and so on.

Now, I don’t doubt that some people are hearing something. And we have Julie Schickling’s recording to prove that there IS some kind of weird noise that can be heard from the Highland Park area, at least.

So, my favoured explanation for the West Seattle Hum goes like this:

The area of West Seattle and surrounds provides an excellent habitat for the Midshipman fish. Perhaps it has even increased in numbers because of some favourable conditions for breeding, as I have mooted above. It may have even capitulated to evolutionary pressure to increase, by physiological and/or behavioural means, the loudness of its mating call. In the past, people have noticed and mentioned the odd sound – perhaps they were down by the river, perhaps it was a particularly quiet night. It is a very puzzling sound, there is no question. Thus is planted the seed for the idea of The West Seattle Hum. Since a similar sound is heard nearby on Vashon Island, this is a very reasonable starting point for the notion.

The mystery of the eerie sound prompts a level of conversational buzz, which, in the internet age, is quickly amplified (not unlike the hum of the fish itself) until it enters the consciousness of the general population. Now, the West Seattle Hum is a ‘thing’, and all kinds of sounds start getting attributed to it. The idea that it was started from the sounds of a fish is not even known by most people, and since West Seattle is close to numerous industrial centres, mechanical sounds from these places become the more logical focus of attention. This idea is fed by a general distrust of the industry in the precinct – a distrust that is in many cases quite justified (my reading tells me that the plants along the Duwamish have somewhat checkered histories when it comes to community safety and environmental responsibility).

Now comes the Labor Day holiday in September 2012. It’s a very mild night after a long stretch of dry weather – unusual for Seattle. The moon is full. People are out and about for the holiday. In the early hours of the morning – let’s say on Saturday at 1am – with the moon full and the night clear, the Midshipman fish, perhaps in greater numbers than they have been in the past, start their song. It’s very weird, and for whatever reason (perhaps via the stormwater resonance idea I put forward above) the sound carries up into the streets. Quite a few people hear it. However, some people hear other things. ALL these sounds coalesce into one huge, vague phenomenon, with as many disagreements about the source of the sound as there are people recounting their experiences of it.

And then, when some scrutiny comes to bear on the idea – when some video proof that it’s the cement plant would be useful, for example, or some hydrophone recordings of the Midshipman fish could be helpful – there is a mysterious silence. The West Seattle Hum has disappeared once more into the background of normal life.

To sum up: The West Seattle Hum is the workings at the Lafarge plant. It is helicopters. It is the next door neighbour’s airconditioner. It is your imagination. And, it is the fish. If I have to lay my cards on the table, I think it is mostly the fish.

Sleepless in West Seattle

I love a good mystery, so what better way to kick off Hummadruz than with a strange story that’s in the news right now: The West Seattle ‘Hum’. The Hum is a peculiar and annoying buzzing/humming sound that has been widely reported in the West Seattle area over the last week or so, but can be traced to nowhere in particular. It appears to be more noticeable at night, especially in the early hours where it is loud & persistent enough to keep residents awake. Comments on the West Seattle blog show just how widespread the phenomenon is, with as many explanations as there are commenters. The blog even features an audio recording of the sound, from Julie Schickling of the Highland Park area:

Audio recording of the West Seattle Hum (the ‘hum’ starts about 28 seconds in).

It sounds like some kind of mechanical device, and there are, apparently plenty of contenders in the district, from large fans at a steel mill, through power transformers to road sweepers and distant helicopters. If the comments on the blog are anything to go by, it varies in dynamic range from extremely quiet to so loud it can be heard even while wearing ear plugs. Surprisingly, aside from Julie, above, no-one seems to have thought to record it (evidently, the curiosity level of sound recordists in West Seattle is fairly low – if I lived there, my first thought would be to head out and get some evidence).

The Hum, it turns out, is not a recent phenomenon – the West Seattle blog ran a story on it back in April 2009, with some commenters claiming they’ve heard it in years preceding that.

If you’ve ever had any experience reading accounts of anomalous phenomena, you will at once recognize the tone of the comments on the West Seattle blog. There’s a distinct impression that all these people have heard something, but a niggling feeling that maybe they’re not all talking about the same thing –  or, at the very least, not experiencing it in the same way. This is one of the problems with odd and diffuse phenomena – it’s hard to sort the wheat from the chaff when it comes to making sense of reports. Human beings are generally poor observers in the best of circumstance and it’s never quite so obvious as when it comes to sound. And, predictably, just to muddy it all up a bit more, there are the pre-requisite fruit loops who think it’s ‘the earth trying to communcate with us’, or aliens, or some kind of government conspiracy – as if things can’t simply be mysterious without having an agenda.

To add to the confusion and puzzlement, the City of Seattle’s Department of Planning, although acknowledging the existence of the Hum, seems reluctant to commit resources to tracking it down. The official Noise Inspector’s reponse to the West Seattle blog’s enquiry about resident’s complaints says, in part:

We are complaint-based, so we rely on the public to notify us of their specific issue and the location of the source. It can be difficult to pinpoint a noise source, especially when you have changes in topography in the immediate area. However, we need to know the potential source location in order to respond with an inspection…. On this particular complaint, we would need neighbors to locate the source before we inspect.

Not quite so easy to do when the ‘source’ is reported from all across West Seattle. That’s bureaucracy for you.

Now, one thing I noticed while reading the nearly 200 comments on the West Seattle blog was that many people were willing to give the location where they heard the sound, and some included even more detail, such as the loudness and the direction from which the sound appeared, to them, to be coming. There’s a not-insubstantial possible database there. So, being the kind of intrepid person I am,  I plotted it, to the best of my reckoning. A commenter on the blog, Ben, had the same thought, and created a Google map of the reportings. I’ve taken my data, and his data and refined it all to reflect reported loudness and also a feasible direction of the sound.

Red dots show occurences of the sound that had geographic location information. Darker red shows louder sound, lighter red shows quieter sound, as indicated in the reports. Green dots are from Ben’s map. Arrows show perceived direction of sound, when included. Highland Park, where Julie Schickling made her recording, is southeast of center on the map. There’s an industrial precinct to the north, another to the northeast, an airport, and a lot of water around this whole district, including a large canal that runs right through the area.

Of course, this ad hoc survey can’t be taken as a proper experiment, as it’s a self-reported, self-selected sample with no controls, so it should be clearly understood that everything we might deduce from this data should be considered speculative. Nevertheless, I think we might be able to make some useful headway if we can keep our assessments rational.

The first thing that seems extremely obvious is that there is no real clumping around any particular area. From this I think we can infer that the sound source is not localized within the West Seattle region. That it can be heard widely down through the area, and that so many commenters find it hard to pinpoint an exact direction, tends to weigh against a particular culprit in a particular location (although something mobile such as street sweeping machines – suggested by a couple of commenters – would remain a possibility).

Significantly, all the directional information, when we have it in the comments (and on Ben’s map comments) tends to point roughly toward the same area: just south of the Eastern Industrial district (disclaimer: I don’t know Seattle at all, and I’m doing this all off maps. I am more than happy to receive additional information & correction from natives.). Now, this could mean that the sound really is coming from that direction, but there are some questions, if that’s the case: why don’t we see clumping closer toward that area, and how should we explain that most of the reports of the loudest occurrences are actually quite a way from that location? We need to consider, also, that psychologically (and logically) there is probably a rational reason to expect that commenters would determine that the industrial areas are responsible, because the Hum does sound considerably machine-like and industrial.

I want to note also that the convergence of the arrows seems to indicate a point that’s significantly to the south of the industrial precinct, to an area that appears to be a container ship loading yard (where, in fact, a commenter drove to attempt to ascertain the location of the Hum). The Lafarge Corporation, a gypsum and cement facility, is also here.

Some other salient points to ponder: the Hum seems to be mainly active at night (although not exclusively) and also seasonal toward spring through summer (although one commenter disputes that). In addition, it is not a consistent phenomenon. It seems to come in surges, the last one being back in 2009. Not only that, the Hum, it turns out, has been reported elsewhere in the area – to the West of Seattle across the bay, on Vashon Island. In this area it is known as the Vashon Island Hum and has a pedigree and history of its own. Vashon Island is certainly way too far away from West Seattle’s industrial areas or shipyards to be affected by the same sound. And yet, it would appear to be fairly similar in nature.

It’s all quite intriguing, as I’m sure you’ll agree.

Among all the speculations and hypotheses on the West Seattle blog there are a few comments in particular that really piqued my interest:

‘Or, maybe it’s just ferry boat noises that can carry quite a ways’ ~ says Toby Getsch

‘My bet is on ship engines, possibly the container ships tied up in port. Could also be the ferries. I have kayaked around the port several times to realize the “hum” I’ve heard from my open bedroom window, since moving here in 95, has the same tonal qualities as the container ships’ ~ said Matt Durham in 2009

‘I’m familiar with this noise too and think it is coming from the sewers. Next time you hear it go to a storm drain and see if it is louder’ ~ said mmd.

‘What’s weird is it sounds loud inside and when you walk out it seems quieter’ ~ said DRW (and was not the only one to observe this)

‘Now that I listened to the clip I recognize the sound. … I always thought it was coming from the water’ ~said tp.

‘Reminds me of a didgeridoo…’ ~ said steph

All of which might be pertinent to a rather surprising conclusion from some researchers from Washington University who suggest a remarkable explanation for the West Seattle Hum: the Hum is produced by a fish. Specifically, they say, it’s the mating call of the Midshipman fish.

Indeed, that doesn’t faze one commenter who seems to be speaking with a fair degree of certainty:

‘It’s the midshipman fish. Happens every time this year. Not sure why it’s more noticeable this season—anything from a few new buildings to greater humidity could contribute to the sound carrying farther. But it’s the fish’ ~ declared J.

A fish? Really? Is that even possible? Well, what does a Midshipman fish sound like?

Whoa. OK, well, that is surely a plausible match for the sound recorded by Julie Schickling. Factor in some resonance & phasing and that is a credible fit. The US public radio outlet NPR also has a story on midshipman fish in which you can hear a lot more of the sound.

The Wikipedia entry on midshipman fish tells us that:

Typical Type II male calls are divided into: short grunts that last for milliseconds or are produced in a series of grunts called a “grunt train,” mid-duration growls, and long duration advertisement hums that can last up to an hour.

Commenter Carol on the West Seattle blog describes the sound she hears like this:

‘Hum is really loud now and it is mixed with a chugging sound interspersed with a tonal whine. Sounds like a construction project. This woke me up’ ~ said Carol

Now that’s a pretty damn good description of the sound in the video and the NPR piece – bit of a shame Carol didn’t have her iPhone to hand. A second commenter also hears a similarity:

‘I always assumed it was the steel plant. However, the recording of the fish sure does sound a lot like that hum’ ~ said West Seattle person

The Midshipman fish is native to the West Coast of the USA, and is quite common, especially in the coastal waters north of Oregon. The Red Orbit Reference library entry on Midshipman fish tells us that:

Mating in Midshipman fish depends on auditory communication; males during the breeding season broadcast a sound usually described as a hum, generated by rapid contractions of the muscles in the swim bladder. The sound can be kept up for up to an hour, and is loud enough to be heard by (and to puzzle) people on nearby land and houseboats; the hulls of the boats tend to amplify the sound to sleep-disrupting levels.

But the fish explanation is not going down well with the folks of West Seattle. It evokes a surprising amount of scorn on the blog:

‘Fish? Get real! The sound I think we’re talking about is mechanical: a very large engine, pump, centrifuge or something like that’ ~ said Bryan Hollister.

The sounds of the Midshipman fish seem extremely mechanical – even electronic – to my ears. If the Hum everyone is hearing is the sound that Ms Schickling recorded, there certainly is a similarity to the fish sound.

‘Anyone who understands the basics of energy transfer has to simply laugh at this “fish” theory. It would take a HUGE amount of energy to create a sound loud enough that it could be heard all over West Seattle and further, even if it was directly emitted from a land-based source’ ~ opined Jason.

Ah, yes Jason, but for anyone who understand how sound works, this does not seem nearly as far-fetched as you seem to think. For starters, your argument is largely self-defeating: if you require that the sound needs a huge amount of energy – assuming it comes from a human made facility as I think you must be implying – then it would be a relatively trivial task to locate it: just head toward the direction in which it seems loudest. The very fact that the directional source of the Hum seems to be, according to the blog commenters, extremly difficult to ascertain, says immediately to someone with training in sound that the major issue is not one of decibels.

Certainly, the sound is loud enough – that’s obvious. But really, to carry across an area like West Seattle, the generating source does not need to be as loud as you might expect, if conditions are right, and if you factor in some other circumstances. One thing we sound people would consider is the powerful force of resonance. You know that effect you get when you run your finger around the moistened rim of a wineglass? That’s resonance. Resonance is a sympathetic vibration that can, and does, amplify a sound quite considerably. Almost anything may act as a resonator, but typically, objects containing a mass of air work best. Think of a guitar body, or a drum. Resonance can have profound effects.

So. Since this post has become rather longer than I’d anticipated, I’m going to break it there and follow it up in the next, where I’m going to propose three  explanations for the West Seattle Hum. I’ll tell you right off the top, I’m favouring the fish.

I wonder if you can anticipate my logic?