I'm just glad they identified the source of the hum, many people are impacted for years by unexplainable sounds, and it is maddening.
It took me and my neighbours a month to find the source of a hum that was resonating with our windows. It was torture, with midnight walks and lurking around potential sources, mapping nearby industrial sites, and questioning our sanity, while our windows were vibrating without a stop. We were very lucky to track it down to a badly installed air conditioning vent 200 m away.
1. A few years ago I spent some time in Falmouth, MA and there was an ongoing battle over newly installed wind turbines. The humming sound was getting to people, including to the point where they were getting headaches. Some people heard it and others didn't. The locals were going to war with the initiative. This article reminded me of that and I checked in on the ordeal. Looks like they shuttered the project and have started dismantling the turbines. It seems like a total failure: https://www.wsj.com/articles/a-green-new-deal-in-profile-115...
2. I was on a solo canoe trip in a remote part of Maine a couple of weekends ago and I kept hearing the sound of a motor start up and then die down. I heard it multiple times along a 25 or so mile stretch of water with the only other sounds being birds, moose rumbling in the woods, and beavers slapping the water with their tails. I chalked the sound up to some wind turbines I had seen on my drive up there and felt justifiably annoyed at the encroachment of the industrial world into my backwoods trip. I did some research when I got home and it turned out that I was hearing ruffed grouse "drumming" to mark their territory. In retrospect, it's an amazing sound: https://youtu.be/q0obByQW23k?t=21
1. Very funny to be reading this. I grew up in Falmouth, and lived there until 2014 when I graduated highschool. I obviously wasn't incredibly attuned to this issue, but as I recall, the only people opposed to the installation of the turbines were a very small, very vocal, and very, very, wealthy minority of people who owned mind-bogglingly expensive beach houses and lived there two months out of the year. I'm fairly certain a lot of the more reasonable-sounding complaints they threw at the project were simply cover-up for their real gripe, that the turbines ruined their view over the bay. I recall an unintentionally hilarious piece of mockup art that was drafted up, comparing the horizon over the water with and without turbines, side by side. They were barely distinguishable blips. It was an interesting phenomenon. Woods Hole, a tiny community on what is essentially a peninsula near Falmouth, is both a center for oceanographic science (WHOI, USGS -- disclaimer, I've worked at both), and a summer home for the insanely rich. The scientific community was largely in support of the turbines, but all anyone ever heard about was how the turbines would be a huge disaster. As I recall, many of the noise complaints ended up being somewhat unfounded.
I have no opinion on anything, FWIW because I actually spent most of my time in Woods Hole. My recollection of all this is from the local paper.
EDIT:
Cliche as it as, the fish bites at Landfall are pretty good! And it was always fun to swing by the aquarium after hours and listen to the seals bumping around in their pool. It's a beautiful place to visit if you ever get a chance.
In truth, the real reason for the disparity in perception is... supernatural in origin.
You see... it's the Curse of Chappaquidick. The sound isn't just the breeze passing through turbines. It's the wailing of the immortal soul of Mary Jo Kopechne, her soul mercifully freed from the watery depths but bound to the wind.
Her soul, unable to find rest so long as the negligent and wealthy haunt her resting place, now eternally floats upon the wind... from Chappaquidick into the Vineyard Sound... across Penzance Point... into the Bay, and back out to sea.
But her spirit is not unkind or unfair. She has no discontent for teachers, scientists, artists, or sailors. They cannot hear her. They say... that only the truly wealthy can hear her cries.
If someone's grown up in the (eastern part?) of the state, the not-very-veiled subtext is quite entertaining with the typical HN cynical bit flipped on.
Cape-affiliated person here. Currently dealing with multiple issues. There is a powerful coterie of real estate agents, lawyers and regional government members here. The environment is invoked like a playing card to create battles of financial starvation and just as easily overlooked when it would interfere with players' plans. One must be very aware of neighbors' affiliations. It's all sport for the 1%, but families who inherited their parents' properties struggle to hang on to them.
Well... size matters. The tip of a wind turbine blade moves much faster (~25m/s, up to 80m/s in the biggest ones) than the tip of a silent computer fan (~5-6m/s, up to ~10m/s in the faster ones). You can make the blades more silent but there's a limit to what you can do when your blades move that fast and are up to 75m long. And any solution that reduces efficiency is probably a no go for manufacturers and operators.
From your links you can see that a 140mm computer fan at 1000RPM is noisier than a 120mm fan at 1200RPM. Even if the motor is quieter at the lower RPM, increasing the blade size is more than able to compensate and make it overall noisier, even with dimples and owl-wing tricks.
And it's not only the decibels that are the issue necessarily but also the frequencies which can propagate quite far and by all accounts are pretty disturbing. That low frequency hum that the blades produce by simply displacing air while they move is not a problem with a computer fan's tiny blades. And turbines come in farms.
That ruffed grouse video is great but does not really do justice to how startling that sound can be. Imagine walking through the woods, no one around, and all of a sudden it sounds like a lawn mower starting up very close to you. It is unbelievably startling, even if you know what it is.
Note that there is a bit of subterfuge in this -- some or all of the lyrebirds mimicking were in captivity and would have heard these unnatural sounds much more than the typical wild bird.
Just across Buzzards Bay from Falmouth was the original Marconi transmitting station for transatlantic communication to a receiver in Norway. My great-grandfather helped build it in 1914! At the time it was the most powerful transmitter in the world at 300 kW. There were 14 440-foot towers in a grid, and it was so powerful that apparently anywhere in town you would get zapped while hanging out the laundry on a clothesline, and you couldn't get a TV signal in town until the towers stopped operating. To avoid interference the receiver had to be located 40 miles away in Chatham.
I wonder what it's like to try to pull a signal up there.
Your comment brings up memories of Lighthouse Beach in Chatham, which has a ton of warnings about Great White Sharks due to the prevalence of seals in the waters. Beautiful place. If the sharks don't get you the radio frequencies will I guess.
Picking up TV and other RF signals near there should not be a problem. Modern transmitters are much different than in Marconi's time. Then they used a spark gap to generate RF, which have a DC to daylight kind of output that GP described. Much like a bad ground on a car ignition system can make a lot of RF noise that really gets around, a spark gap transmitter puts out a signal EVERYWHERE. Which is why it affected so much.
Modern transmitters are tuned and filtered so they can coexist with everything else.
2) It's amazing how perspective changes with more information. It is very odd how much that sounds just like a mower having difficulty starting, and is exactly the conclusion I would have jumped to it being. Glad you were able to get a better answer.
Yeah, I thought it was a generator or mower at first. It's just quiet enough that I mistook it for a much louder sound that had grown faint due to my distance from the source.
I went deeper down the rabbit hole, and it is their mating call / territorial signal. The drumming sound is actually created from a vacuum effect caused by the particular movement of their wings. https://www.youtube.com/watch?v=vERkh23mp64
I think the complaints about Falmouth wind turbine noise are eerily similar to complaints that wifi gives people headaches. I don’t think they are founded in reality.
My parents lived up that way, and the amount of NIMBY-ism regarding offshore turbines is staggering. I suspect you may be right, and people just latched onto whatever claim got the turbines shut down.
It is also possible that they generate the sound of the same frequency, but coming from multiple sources it can compound in some areas to be louder than elsewhere - and those areas could change with the direction of the wind.
This is purely speculation from my side of course, as I've never been there.
How are those similar? What about this story leads you believe that these people are claiming to be hearing frequencies outside of those known by science to be audible to humans?
So funny to hear your story about your canoe trip. When I hiked the AT in 2002, I spent the first several days having the same experience you had. I thought I was hearing things, then I thought I was much closer to civilization that I expected and hearing lawn mowers, finally talked to other hikers and got the story.
Same think was driving me nuts in the BWCA, camping in areas where there should not be any engines. Came back all salty that someone must have a gas powered well or something. Outfitter said I should find a recording of a horny grouse... and I'll be damned, that was it beating its wings. Last trip over Memorial weekend we had one nearby, and it brought nothing but smiles.
So how has this affected your life since? Did you stop assuming things more? Do you like the sound of lawn mowers because they sound like a natural sound?
Not a huge change - a smile rather than a tut when I hear the distinctive sound. The BWCA is a protected area where they really try to keep the water clean. Folks have cabins near the area (heck, some day I'd like a cabin up there) and I was sure someone had a well pump or something that was spinning up sporadically. Changed my perceptions of the noise - rather than assuming I'd failed to get far enough into the wilderness, I came to realize I'm in the thick of it.
Headed back up there in a couple days. Hope to hear the grouse pounding their wings, the moose walking through the water, and a wolf howling away.
When I thru hiked the Appalachian Trail I nearly went mad trying to identify that “drumming” sound. It was so deep that it felt like it was coming from inside my body, and I was concerned that it was some strange condition.
Finally, at one point I asked a group of other thru hikers if they had experienced it, and they all excitedly nodded, but none of us knew the source. Finally, some local day hiker said “oh, it’s probably just a grouse”. And the mystery was solved. Many of us were very confused for months!
This is funny, the first couple of times I heard it I also wondered if I was going a bit mad. When you are out all alone and you hear a sound that you can't explain I think it's pretty natural to think that.
Your description reminded me of a similar sound on my first night on anchor with my first chartered yacht. Turns out it was a fan in our inverter that was somehow switched on and it completely drained both our batteries (wrong installation) overnight so we couldn't lift the anchor nor start the engine in the morning
I've had this happen. Our boat has a separate battery for the generator, so normally if you accidentally drain the main and engine batteries, you can recharge via the generator. But during maintenance someone reset a switch that connected the generator battery to the mains without realizing it. We were in the proverbial middle of no-where - I had a 1+ hour row in my dingy to a remote camp to find someone to rescue us (jump-start the generator).
Now I never leave the dock without one of those portable car-starting batteries, completely disconnected from everything.
cried a little and called the charter company. Spent the day swimming at the anchorage waiting for them to show up with a new charged battery (the old ones were so discharged they couldn't even be charged by a fresh one)
Dude rented a charter. It would be pretty silly of the charter company not to have some kind of "rescue" provision, wouldn't it?
We had a very similar story, except we were the first to rent the boat at the start of the season and the battery bank hadn't been very well tested before they gave it to us -- a few had gone off over the winter. They drove out from HQ, replaced the bad ones with fresh stock from their van, and sent us on our way.
You would have trouble landing without the engine though. Better not to risk it if there's no problem with being anchored there, and just waiting for the fix.
It's possible - I did the RYA training which describes the theory of it and we even involuntarily attempted it in practicals (gearbox broke and it wouldn't go forward). But it's definitely not easy. In the end we hit a spot in the marina with absolutely no wind and had to swallow our seamanship pride and back up there
In the marinas you have limited maneuvering space and with sails you are limited in which directions you can go - directly against the wind is not possible, you need to zig-zag. Slowing is also a bit more difficult. To add to trouble, marines are often built in places with less wind (of course) and wind might change direction during landing. Note that it's still quite possible, just more challenging, risky too I guess, and also forbidden in many marines. But it's a good exercise, it makes one respect ancient mariners even more.
Extending this comment, before motors it was routine to have to wait for favourable winds, especially in harbours and confined waterways. Here's the famous navigator James Cook setting out from London on his second voyage:
"I sailed from Deptford, April 9th, 1772, but got no farther than Woolwich, where I was detained by easterly winds till the 23d, when the ship fell down to Long Reach, and the next day was joined by the Adventure. Here both ships received on board their powder, guns, gunners' stores, and marines."
So the "Resolution" managed about 8km on the day of departure from the London naval dockyard, then remained anchored in the river for 13 days waiting for the wind to change direction, finally managing 16km to the victualling dock.
Low-grade humming is exhausting anyway. That's one of the reasons people are so tired after a long plane flight, despite just sitting there.
Giant stationary installations with very loud noises tend to cause weird noise issues. It's a lot of unfocused, or weirdly focused sonic energy that can't be heard from a little further away, but at exactly the right (well, wrong) place, it can get re-focused, leading to a droning noise that starts and stops unexpectedly. A good example that shows this phenomenon is real, despite being invisible is the Listening Vessels[0] exhibit at the Exploratorium or similar, with two giant parabolic sound reflectors.
For the wind farm, the issue isn't just turbines, but that specific turbine, down to the serial number and the serial number plate, at that exact location, temperature, humidity, causing a resonance in a specific resident's door, miles away. The resident may be able to replace, eg, the door, but often there are factors outside of the resident's control that contribute to the issue. Like the siding on the neighbor's house, or where their car is parked.
Ideally an acoustical consultant would be brought in during the design stage (just like SREs should be brought in during the design phase of a new service and not 5 minutes before it goes live), but that almost never happens, as we see (well hear) here.
At least in this case the noise can be heard by everybody. Imagine this noise coming off the bridge, but it's only audible from your bedroom Tuesdays when its cloudy. And none of your neighbors can hear it. You'd think you'd gone mad!
> Ideally an acoustical consultant would be brought in during the design stage (just like SREs should be brought in during the design phase of a new service and not 5 minutes before it goes live), but that almost never happens, as we see (well hear) here.
Noise studies by qualified acoustical engineers are the rule not the exception in many jurisdictions.[1] But these only go so far, because the model of the predicted noise emissions from the as-yet-unbuilt turbine is only so detailed.
For what it's worth, no matter how much engineering you do there are always people who think they can hear something that can't be measured and won't be convinced otherwise.
On the other hand, a thing that really does reduce complaints is paying a community dividend to everyone who lives nearby (instead of just paying the owners of the actual land under the turbines).
Anecdotal evidence, but I have the same experience as well. I’m not from US, so I will assume it’s a different type of turbine.
Wind turbines were installed near our village and my family started hearing sounds and feeling vibrations. I didn’t hear and don’t hear them when I return there, but it forced my parents to leave their home.
It’s a horrible feeling, especially since people don’t believe you. It can hardly be measured, because people with the correct equipment don’t pay attention to you and other people think you’re crazy.
Actually, if anybody has more information on how would I go around fixing this issue or which party should I raise this with, I would welcome that. It’s been more than a decade but the turbine is still there even though affected people have moved out.
German researches recorded the sleep patterns of 397 residents in areas where there was previously no mobile reception.
After erecting 10 towers, many people complained about a change in sleep patterns. 5 of the 10 towers were turned off though so had no actual effect. Just the believe was enough to cause problems. [0]
RE: #2. I remember the first time I heard that sound when I moved from the city to the woods of NH. I thought someone was trying to crank up some kind of motor, too. Then I eventually caught a glimpse of a ruffed grouse doing its thing. Neat.
"felt justifiably annoyed at the encroachment of the industrial world into my backwoods trip"
Sure, yes. The annoyance is justifiable. And I do not mean to come off as combative. I just wanted to say that our alternative forms of energy also encroach on the natural world in other ways (climate change, dirty mining, etc). So while turbines might more viscerally feel like an encroachment on nature, we must remember that they may displace some more destructive form of energy generation. I am not equipped to argue definitively that they are better, just that the visibility of wind turbines might influence our perception of them.
Speaking of #2, awhile back I was wondering what noises emus make and it turns out to be something I wouldn't have ever expected any animal to make: https://www.youtube.com/watch?v=KOLF7JhW2Iw
When I lived in Nob Hill, there was a quiet long beeping sound that could be heard every couple of minutes - imagine a quiet booooop and you're pretty much there. Definitely sounded electronic. The weird thing was I could actually hear it on quiet days in a large radius in Nob Hill. It didn't seem to be localized on my house.
I was never able to identify it, and searching online gave me nothing.
I hear this all the time. I was just talking to someone about it. It’s not everyday but it’s frequent. I hear it mostly in the morning and at night.
It’s always the same length, about a second. It’ll come in pulses of 2 or 3 usually. Spread out a few minutes a part. It definitely sounds like an electronic sound. Almost like a sci fi satellite sound but deep in the water far away. Or maybe a far away whale mourning or something.
I just traveled for 3 months and heard it spread across 10 cities.
Power companies transmit a signal at certain times of the day through the lines. This controls devices that can switch between day and night mode. My ceiling fans will buzz when it's happening. Sounds almost like the old SMS interference you'd get with FM radio.
In the Mission I could occasionally hear foghorns, which made no sense to me. It was generally around first light in the morning. After quite a lot of digging, including making heatmaps of where ships parked, I traced it to Anchorage No 9, which is basically a parking lot for giant ships. You can see it when crossing the Bay Bridge.
Pretty interesting hypothesis! I don't think so, though. It was a fairly electronic sounding boop, almost like a low sine wave. A fog horn sound has more acoustic qualities to it. Also, if it was a fog horn, I don't know why it would only be audible in Nob Hill and no where else I've been in SF.
Yup, the tone at 0:08 is pretty much the exact tone I heard. Mind-blowing. Never would have imagined that's what a fog horn sounded like. I expected them to all be much deeper tones like the ones that come a few seconds later. I guess there must be weird acoustic qualities that make only the higher toned ones carry into Nob Hill.
If it's anything like the most common fog horn that the USCG uses across the country, it's a 273Hz tone (though I don't recall the waveform, most likely sinusoidal).
As of 8 years ago, they were using the FA-232 model fog horn, the circuitry was designed in the '70s and uses discrete BJTs on the boards to generate the tone and drive the "speaker".
chirping smoke alarm? Saw a YT clip of a dude hunting for annoying beep with army of audio recorders, turned out to be battery depleted fire alarm under the stairs.
Considered this too, but there are two reason I ruled it out:
1. The beep was very long - maybe a second or two - much longer than smoke alarms.
2. I could hear it blocks away from my apartment. No smoke alarm chirp would carry that far.
I was going insane at my old house because of 'the hum'. It started when I installed double pane windows. I think they dropped the ambient noise to the point where the hum was obvious.
Any idea what you'd use to track down very low frequency noise sources(i.e. 15-60Hz)? I don't think a lot of sensors do well in that range.
Never tried but i would go for a geophone. The datasheet of this one https://www.sparkfun.com/products/11744 says that it has reasonable response along that range.
I got an infrasound microphone but all it did was demonstrate that the hum I can (barely) hear (and that my partner cannot hear) is real... and that indeed it doesn't go away when I cut power to everything within 500ft of my home (which I believed from my own observation, but wasn't completely sure of).
Get an audio spectrum analyzer app for your phone, and enable its log-X scale. Very useful for this sort of thing. The FFT will reveal sounds you don't hear yourself.
They are indeed cool, but no math magic can help you if your microphone is not picking up the signal. I don’t have datasheets for mobile phone microphones but lets look at some professional ones. The Senheiser MD 46 goes down to 40hz. The Behringer MC8000 goes down to 15hz. These are just two random samples I looked at to illustrate that its not obvious that a microphone will even have a good response down to 10hz.
For a good year I used to here this high-pitched whine when visiting my grandparents. I could hear it throughout the house, and though it was either a faulty vent, or seagull chicks on the roof. It was not constant, and rather intermittent.
I checked everything, but nothing. Asked my grandparents about it, but they couldn't hear any noises. Finally I got a friend over, and he could hear it clear as day.
One day I noticed my grandmothers hearing aids lying in a casing, and it turns out those were the source of noise. She'd forget to take out the batteries, and they would create a negative feedback-loop that came and went.
A couple years ago I got moved to a new office where I could hear an awful humming noise from the light ballasts in the ceiling when the lights in a showroom/lobby downstairs were turned on. None of other dozen people in my office could hear it.
I feel like I wasted a bunch of perfectly good political capital at work in my fight with building management to get them to fix the lights. They finally replaced them with ballast-free LEDs after six months.
Same thing happened with me and getting a full spectrum light for a windowless office. I left the job not too long after due to an abusive manager. Certainly wasted political clout on the push for health.
Mysterious sounds are very intriguing. My favorite is the mysterious sounds heard by Lewis and Clark on their expedition. This article goes down a bit of a rabbit hole, but it starts with a fairly good summary:
http://www.lewis-clark.org/article/1468
My backyard backs in to a strip mall with an auto mechanic shop. We hear a high pitch sound some times of the day and when we step outside to inspect, we only hear a different sound from the shop behind - a typical machine running, but not necessarily unpleasant. Turns out the walls are able to mask the lower pitch sound somehow and let in only the unpleasant higher pitch sound to the inside of the house. I am not sure how to explain it to the shop owner, but we are just going to ignore it for now. I guess I need to look into insulation options :)
Had that where I live, for the first year. San Francisco as well (it's windy here!) Finally after about a year of it, figured out it was the turbine ventilator on my next door neighbor's roof. She was a bit elderly and didn't seem to want to do anything. Luckily I realized I could reach it from my own roof. So I jammed a stick in it and it never spun again. Problem solved!
It's just an attic ventilator. And yes I know. My sanity outweighs the air quality of her attic. And I told her first.
(FWIW she's a very nice lady and has long since sold the house and moved away. I told her I had done that at one point and she just chuckled and didn't care)
I get woken up once a week by a sound similar to the one the Golden Gate Bridge is making. It starts around 4am, except it comes in short pulses. I recently figured out it was the breaks on the garbage truck that services my neighbourhood. They make a really loud high pitch hum every time it stops, and when the truck isn’t particularly close by, you can’t hear the rest of the truck sounds, but you can hear that hum very loudly.
The local council didn’t really care when I told them. It doesn’t bother me too much because I get up quite early anyhow, but I imagine this truck would manage to bother a rather large number of people every week. I wonder if the sound will go away next time it’s serviced.
Nice work! Any specific techniques you used to identify the source? I've longed for the day an inexpensive or software based acoustic camera comes into reach. So many sounds I've been on the hunt for in the past an even unto today.
https://en.wikipedia.org/wiki/Acoustic_camera
In my last apt, once in a while I'd start hearing a far-off hum, and it would always make my wifi go out. I eventually tracked it down to a huge backup generator for a commercial plaza a few blocks away, but telling my ISP that a distant hum cuts out the internet every once in a while wasn't going to get me anywhere.
Reminds me of a prank that some co-workers pulled off: they bought some gadgets that would make a cricket sound but at random, irregular intervals, and hid it in a person's office. It drove that person insane as they slowly and methodically moved all pieces of furniture out of their office.
I hear what I suspect is the subway on the next street over moving underground periodically throughout the day. There isn't even a station there, I just hear a low rumbling that moves up or down the route.
I tried using baudline[1] (a 20-year-old program!) but it didn't work out-of-the-box on my current Linux installation. Instead I found something called Sonic Visualizer[2], which, while not real-time, worked out of the box. Using Pulse Audio 'pavucontrol' it was easy to configure Sonic Visualizer to use as its input the 'monitor' channel, i.e. capturing the audio while the video played on Twitter.
I'd love to get baudline working again since it's able to run in realtime.
It looks like the main tone is at 440 Hz and tones at 400 and 480 Hz come and go. Not sure what to conclude from this. :-)
"As low as A=435"? The reality is much stranger! Baroque groups such as Philharmonia Baroque Orchestra, and American Bach Soloists, and many others, routinely perform at A=415, which is the standard accepted "Baroque" pitch these days.
Earlier music is sometimes performed down around A=390.
In tuning systems what one really cares about is the ratio between pitches, not the frequency of a specific note. You could have A=440 and tune to just intonation and that would sound different from A=440 and 12 tone equal-temperament.
It displays an a message "all input devices disabled" and when I right-click and choose input→devices, the only available option is the loopback tone generator.
That's because it uses OSS, not ALSA. You were right about it being old :D
ALSA can either do in-kernel OSS emulation (loaded via eg `modprobe -a snd-{pcm,mixer}-oss`), or shim the existence of /dev/audio via an LD_PRELOADed library by doing `aoss baudline`.
PulseAudio offers a userspace LD_PRELOAD shim as well, via `padsp baudline`. I have no experience with this approach (nothing I'm running has pulled in PulseAudio yet).
On my end the userspace approach just gives me "No such device or address SNDCTL_DSP_SETFMT", which I don't have a solution for. I suspect it's because either my hardware (HP EliteBook 8470p, IDT 92HD81B1X5 codec) or kernel (Debian 10, 4.19) are sufficiently new they're confusing the program. The kernel OSS emulation works for me though. If this is a hardware quirk the userspace method may work for you; the other path would be bisecting the kernel to see where it "broke".
Next up I got a lot of "/dev/audio requested fragsize ignored". If you don't get this error (and it Just Works), you can stop reading now :) but
http://www.baudline.com/faq.html#fragsize_ignored explains that this is basically fixed by tweaking a bunch of settings to see what sticks. I must admit that after reading "first try this option... then try this one... then this one... then try all possible combinations of all three..." I immediately went "haha nope" and headscratched to see how I might make the computer make the effort - because, you know, it probably wouldn't work anyway and all that.
Because this old program is using Motif, the ASCII contents of the (what I presume are) PolyText8 X11 requests are visible in strace :D so it's possible to use grep to identify the "requested fragsize ignored" dialog boxes being created. For some reason repeatedly starting and killing the program in a tight loop makes the message box occasionally appear with 0x0 width/height and no contents (yay, race conditions...), but grepping for the title ("error message") instead always works.
Identifying successful loading is a good question, but if we define "successful" as "isn't promptly SIGPIPEed by grep exiting on first match within like 50ms", we can wrap the grep with `timeout` to kill the program on successful run within 500-1000ms, with a nonzero exit status.
Putting those two ideas together and shoving in all the possible parameter permutations, we get:
fragsize=({1..10}); infrags=(1 2 4 8 16 32 64 128 256 512); samplerate=(4000 5512 8000 11025 12000 16000 22050 \
24000 32000 44100 48000 64000 88200 96000 176400 192000); samplerate=($(printf '%s\n' ${samplerate[@]} | tac)); i=1; \
t=$((${#fragsize[@]}*${#infrags[@]}*${#samplerate[@]})); for FS in ${fragsize[@]}; do for IF in ${infrags[@]}; \
do for SR in ${samplerate[@]}; do c="./baudline -fragsize $FS -infrags $IF -samplerate $SR"; printf "\r%-55s (%s)\e[K" \
"$c" "$(((i*100)/t))% $i/$t"; DISPLAY=:1 sh -c "timeout 0.5 strace -s999 $c -iconic" 2>&1 | grep -q 'error message' \
-m1; (($? != 0)) && echo -e "\r$c\e[K"; echo "$c" >> baudline-ok.txt; ((i++)); done; done; done; echo
About 25% of that is putting nice status messages on the screen, and noting (what might be) successful runs in `baudline-ok.txt`.
It assumes ./baudline is in the current dir.
On my midrange i5 with an HDD, a timeout of 500ms (the '...timeout 0.5 strace...' bit) is adequate. If it thinks all runs are successful this may need to be made longer, like `timeout 1` (1 second).
The contents of `samplerate=(...)` were fished out of `./baudline -sysinfo`. Your output from that command may be different, in which case you might substitute that instead. FWIW I have the `... | tac` bit in to reverse this simply because higher sample rates are better, and if you want to ^C it early you get bigger sample rates first :D
With the above parameters (fragsize 1-10, infrags =Nx2 from 1 to 512, 16 samplerates) there are 1,600 iterations, and it takes about ~5 minutes. My laptop's fan kicks in :)
Because of all the flickering (<--note!--) from the program being repeatedly started and exited 1,000+ times, I added DISPLAY=:1 to start it in a nested X session so you can minimize the X server window and continue with other things. I use Xvnc; Xnest or Xephyr are possible alternatives. I also noticed the convenient -iconic parameter, and verified that if you start a window manager (I tested openbox) in the nested X server it starts/quits slightly faster. You don't need to bother with an extra X server and windowmanager; just remove the DISPLAY=:1 bit and wait for everything to finish. Note that the window opening/closing will completely steal all input focus and make work temporarily impossible.
When trying to optimize the first version of the above script I decided to try and launch the program with all possible parameters simultaneously >:D. Theoretically/technically speaking this should have simply made the hardware get very overloaded and slow for a period, and maybe swap; what actually happened is that I ended up having to start over from scratch because the kernel hard froze :D (it was indeed a hard lockup, there's no panic info in syslog :( ). I might try doing that again at some point, looks like ALSA and/or my audio driver have a few chinks in the armor there. FWIW, I've run the above script (which is decidedly non-parallel, of course) many times while I was fiddling with the status bits, and had no lockups; but Baudline may also do interesting things on your hardware when launched 1,600 times in rapid succession.
¯\_(ツ)_/¯
(You're probably fine, just :w / ^S first)
Caveat emptor (and major confuzlement): This program is very weird. Yesterday it worked with a samplerate of 11025Hz. Today it only likes 8000Hz. I have no idea why. Different parameters may work on different days??
Apparently they knew about the hum in advance. Under CEQA they should have had to do an Environmental Impact Report and hold public hearings. Someone is bound to sue.
UPDATE: The sound is intentional. Or, at least, known about in advance.
According to a statement Saturday morning by Paolo Cosulich-Schwartz of the Bridge District, "The Golden Gate Bridge has started to sing. The new musical tones coming from the bridge are a known and inevitable phenomenon that stem from our wind retrofit during very high winds."
Cosulich-Schwartz adds: "As part of the design process, the District did extensive studies on the impacts of the project, including wind tunnel testing of a scale model of the Golden Gate Bridge under high winds." Those tests, seen in a video here, showed that the bridge "would begin to hum" when air passed through it more freely.
This sounds so beautiful and desolate, reminding me of a combination of the first two tracks from Aphex Twin's Selected Ambient Works Vol 2, disc 2, in particular "Blue Calx" and "Parallel Stripes" starting from 40 seconds. [0]
That was such an insane thing to discover my first time on the BART. I’m sitting there thinking a catastrophic accident is about to occur, but everyone else is just on their phones... oh, that’s just the screech!
From a Londoner's perspective, this is giving me tortured flashbacks to travelling on the Jubilee Line. It's physically painful to hear once you start speeding up inside the tunnels.
I travel on the Northern line on the London Underground to get to work and the sound of the trains nowdays hits 100dBA or more of extremely loud screeching: https://i.imgur.com/04YwBHJ.png
I went as far as lodging an official complaint and was told that to deal with capacity trains are running more often and faster than they have in the past, hence the increased noise. Furthermore due to the Northern Line having been built before environmental noise regulations were passed, it's exempted so Transport for London aren't planning on doing much about it.
At the risk of sounding like a curmudgeon - between always on ear buds and mass transit noise we're risking a generation of kids suffering hearing loss well before their time.
My understanding was that all rail systems since roughly forever use tapered wheels. Primarily to reduce wear, by having the tapered wheels self center instead of grinding against the track.
It's really odd that they seem to just roll that out in 2017?
> unlike the cylindrical profile which again just steers with the flange basically rubbing against the edge of the railhead.
That's crazy. That means that the wheels are actually slipping when going around a corner, because the wheels are all the same diameter. Unlike conical wheels, which are essentially self-steering.
How could the BART trains possibly have cylindrical wheels? Conical wheels have been used on trains for ages, so that's seems weird. But doing some research, it seems that, yes, they were cylindrical:
> Queensland Railways, for its first hundred years, used cylindrical wheels and vertical rails. With non-inclined rails and cylindrical wheels, the wheel squeal from trains taking curves on that railway was slight. After adopting coned wheels and inclined rails from the mid 1980s, the wheel squeal from trains curving at the same location and at the same speed decreased immensely. Some modern systems, such as Bay Area Rapid Transit (BART) in San Francisco, use cylindrical wheels and flat-topped rails; BART is now switching to conical tread to reduce the noise caused by flange/rail contact and loss of adhesion of one of the wheels on curves.
"BART says", but as of 6 months ago I was compelled to buy ear plugs for my commute. There's a stretch just before West Oakland (Westbound) that I'm near certain has given me ear damage.
Did you watch the videos, specifically of the guy in what seems like a golf cart going over the walking section of the bridge? It sounded horribly loud, louder than the guy who was crying about how loud it was
The bart didn’t do that when it was new. Apparently, standard railway maintenance involves grinding busy tracks down on a regular basis (so the track has a round crown on top instead of being flat).
Of course, the BART system simply fails to do the maintenance. I used to commute through the transbay tube and would happily join a class action suit over the hearing loss.
Berlin has some absolutely beautiful church bells. The overtones and reverb from all the walls are so chilling, it makes you feel like you're inside the bells or something. I recorded one of them: https://sndup.net/2h7t/St+Joseph+Kirche.m4a
I saw a video on Twitter from what looked about half a mile from the bridge - sounded like Lustmord to me. All it needed was some ethereal demon howl and it would have been perfect.
Yes, it cannot be a 24/7 thing, the harp/bridge is too loud. Also, putting resonances into a suspension bridge is likely to be unsafe.
That said, like the chiming of church bells in a village, it may be used selectively. I can imagine some Burners quickly putting up an adjustable mechanism to have the bridge sing/chime.
Something that can point into the wind correctly (to some degree) and then be readjusted to turn off. Possibly to make more than just one note, like a carillon of bells in a bell tower.
Maybe at the tops of the hour it can turn on/off, like a church bell, to signal the time. Or on special occasions like New Years Eve, the 4th of July, etc. Or for swearings-in of a mayor's term, etc. Heck, even as a warning system for earthquakes.
Having that loud of an instrument, powered by the wind, and then controlled by a few hundred actuators or a bridge-worker/bell-ringer moving steel beams in and out, it's just too good of an idea.
If something like that could be made to work, on such an iconic bridge, well, that's a whole new industry. People have done 'love locks' for years now, chiming bridges would be a great idea too.
There is already enough noise pollution in the world. We don’t need noise graffiti that indefinitely blasts sound 24/7, even after the perpetrator is long gone.
If you really want to help build a dystopia, you’d probably have a bright future in advertising. Apparently electric car noises were less about safety than branding.
Some of the car manufacturers wanted their cars to blast sound logos all the time, but they were afraid the first movers would be lined up against the wall and shot.
Electric cars were the perfect excuse to do it anyway and blame regulators, so their lobbyists made it happen in the name of safety.
I joked with a friend today that with San Francisco being San Francisco, someone will have a system for making it play Carol Of The Bells by next week.
When I visited Japan last year, I drove a mountain road one day with these guard rails/posts that were specifically made so that as cars pass by they emit a tone of a simplistic song (if I'm remembering correctly it was "Itsy Bitsy Spider"). Thought that was super interesting and a cool experience; a literally cool experience, since it was snowing and my friend told me so I made sure to have my windows completely open so I'd be able to listen.
I bet they aren't exactly happy with their day-to-day either. It's just we are somehow normalizing and glorifying suffering instead of encouraging people to walk an extra mile to get out of it.
To get direction and location, you need acoustic samples from multiple widely-spaced locations, all synchronized. Human ears are not wide enough apart to directionalize low frequencies, but with a baseline of tens or hundreds of meters from separate cell phones, it's not hard. Run a correlator, line up the samples, compute the hyperbolas of constant time offset, (like GPS and LORAN) and find the target.
This needs an app with timing accurate to a millisecond or so. Can you get that from cell phones? The built-in clock synchronization isn't that good. The GPS receiver has more accurate time, but you may not be able to get at that.
Nit: Human sound localization is 'good' from about 200Hz to about 1600Hz. Other posters have the sound at ~440Hz, so humans should be able to localize the sound fairly well.
In this case, I think they're mostly referring to "The Hum"[0] that others have been talking about, since the article is about the source of this noise. When it's lower frequency and not this easy to locate, it would be great if there were some other way to go about it.
I agree. For several years I have been looking on and off for a layman way to locate a source of a sound, but haven't found anything.
A solution like this could resolve many of the lingering "hum" cases. Often they are only heard by a few people, and those in charge of environmental control don't tend to take it seriously because "they don't hear it", or because they or the higher-ups are hiding something.
Acoustic consultants are extremely expensive, may require many hours if the sound is only apparent during random hours, and even then may come up with nothing.
An app that would at least be able to give a good estimate of the direction from where a sound is coming would be extremely helpful.
You need to maintain millisecond sync while the devices are widely separated, possibly for hours. Cell phone clocks are not millisecond-accurate over hours. The idea is that a group of people all download the app and walk or drive around the area of interest collecting time-stamped audio and sending it to a server.
Amusingly, data collection would be easier with analog technology. Get some VHS walkie-talkies, and, at the base station, feed all the channels into a multitrack tape recorder like musicians use. No sync problems.
For sounds transmitted through the air, ms precision is really necessary at distances of more than a few meters. Network time should be close enough at 10s or even 100 ms (roughly speaking < 10 meters of error - which is good enough to set up a local monitoring net via wifi with <1ms/<30cm of error).
I guess this is complicated by the fact that the speed of sound through the ground is ~6km/s. Rather faster than the speed of sound through the air. Multiplying those errors by 20... but 200 meters of error isn't that bad. A powerful local network with no latency would then be enough to isolate further.
I think you’re missing how easy it is to do these days.
It’s pretty easy to do with NTP synced devices. I’m lucky enough to have a fleet of devices sync with GPS and the PPS signal. It’s pretty amazing to/fun to do latency tests, you grab a time stamp and ship it to far side and time stamp the arrival. Voila single direction latency measurements.
I hope somebody has a chance to make high-quality samples/recordings before it's fixed. I doubt we'll get the chance to hear an instrument like this again, accidental or not.
The engineers said it's a known outcome from high winds. It seems they made a conscious choice to decreasing the structural risk of extreme wind hitting the bridge in exchange for increasing the noise it generates
It's going to be and should be fixed or at least alleviated. They probably thought there would be some noise but not like this. Some model prediction most likely didn't encompass some environmental element.
I honestly think this is awesome and beautiful, though I might feel differently if I lived nearby just because of how relentless it is.
I remember years ago I had the idea that if you could design construction equipment to rotate/oscillate/whatever at frequencies that were harmonic with each other, construction noise would become musical, almost like a very loud set of wind chimes.
There's a scene like that in the 2003 version of Zatoichi. But it's with manual construction equipment, so the musicality is rhythmic rather than harmonic.
I rode across the bridge in high winds last week and I thought that the bridge might be failing somehow - the sound was almost unbearable - I thought a serious safety issue was potentially occurring because of a structural frequency effect. I guess the good news is that there is no emergency - bad news is maybe ear plugs on bike rides on windy days.
Holy moly I can hear this from the Inner Richmond at night, WHILE IN MY BED. I thought my tinnitus was doing something new, but it's the freaking bridge!
He went on to say "check out this sweet deal I got on these sony WH-1000XM3's via my Amazon afilliate link below. Don't forget to smash that like and subscribe for future philosophical updates."
To be fair, the Sony WF-1000XM3's are awesome and I love mine. Living in a big city is so much more pleasant with noise canceling. It can be surprising to take them off and realize how loud the environment around me actually is.
Pretty much the only good thing about the lockdown was the massive reduction in sound levels in London. Just off Old Kent Road which means traffic noise dropped, plane noise disappeared[1], general hubbub of the feral children vanished, no late night parties at the community centre, etc. It was as close to blissful as I've encountered in London.
[1] Normally one every 5-10 minutes from 0500 to 23000 since we're on Heathrow approach and not far off City's path.
Lots of good things about the lockdown from the aspect of peace, quiet, nature, clean air, reduced light pollution, and more. It just comes at a cost that society isn’t willing to bear.
It looks like you may have misunderstood what I was saying. The polls pictured that linked to say America is united to defeat coronavirus even at such a high cost. My argument is that this price that nets us these wins of peace, quiet, reduced pollution, etc etc comes at a price that society would not sustain past this crisis.
Ah, sorry, I get it now. And I suspect you're right.
FWIW, my big hope is that we can reconfigure our economy to work without conflicting with those wins. (The climate is still changing, so we have to reconfigure anyway.)
In LA, the city has used the downtime to ramp up road and metro construction, and buildings have been shooting up at a faster pace. I drove past one of the neighborhood pits that will turn into an apartment eventually and they had six excavators at the site all digging at once. Instead of road noise, now I get to hear drilling and hammering and dump trucks backing up and having rocks tossed into them at 7 am.
this is fascinating! i wonder how long it will take them to do something about it? seeing the video, i almost wish they'd keep it, but i don't live nearby, so...
i found a couple more video examples of accidental acoustic wind effects in architecture -- but it looks like these aren't as ever-present and loud as the Golden Gate Bridge is right now.
in the Beetham Tower case, apparently the architect lives in the tower's penthouse. i bet they're frustrated that none of the fixes have completely remedied the problem.
Was in Manchester to see Metallica last year, Beetham Tower is spectacularly ugly in person though I suspect it'll be around long enough it'll become a much loved icon.
Maybe they should find a way to generate electricity from the bridge, it sees plenty of wind practically every single day for the same reason the SF bay is great for sailing.
It depends. Doubt that would affect wind resistance if the shape stays the same, only the vibrations would be partially dampened by added piezoelectric generators. Draining some mechanical energy by turning it into heat+electricity might even improve the mechanical properties.
If instead of the slats they installed thousands of tiny vertical axis wind turbines, perhaps much of the energy would be used to turn them rather than vibrate the air. I guess it might also make a noise, but maybe quieter or less grating.
Lisbon also has a bridge that you can hear from miles away: one lane in each direction has a surface made of metal grating which makes a loud hum when cars drive over it.
People who live nearby don't notice it (strange looks if you point it out) but I think it's sad that it's impossible to escape the constant noise in certain places.
Were just there last fall, and yeah, it's incredibly loud, both going over the bridge, and from the viewpoint, and.. well, pretty much all over I imagine. I will say, I didn't notice it from the city side, though -- perhaps because of the way the city curves away from the bridge, or because you're "underneath" the sound rather than above it.
Another relevant bit about Lisbon's 25 de Abril bridge is the common misconception that it was designed by the same company as the golden gate, as it looks similar and also has a red paintjob, when it was in fact the company that designed the Bay Bridge, which is even more similar (except for the colour).
I guess there aren't all that many companies that can build such massive bridges. Now I'm wondering where else I might have seen a bridge made by the same people.
They finally found a way to reduce the cost of real estate in SFO! Seriously, you have to wonder how someone can actually think this is OK when it can be heard from far away at all times and people crossing it are reporting it to be unbearably loud.
My prediction is this will be added to the long history of engineering disasters. It's OK, this is how we learn.
I’m curious if there can be an impact on the wildlife out here. Animals don’t understand what the noise is, so can it disorient them in some way that could have a harmful effect?
Another 'cool' mega-instrument is the Earth Harp. Instead of transverse waves (plucking) the strings, you use compression waves (pushing) in the strings to make the vibrations. Due to some physics here, you then need a very large resonator to hear the sounds. Essentially the Earth itself. Here's a good video from the Burn at an Earth Harp performance: https://www.youtube.com/watch?v=c66w_pPnO-s
Every engineer, not just the ones building bridges. I was required to take an Engineering Ethics course that covered Tacoma Narrows as well as other incidents, such as the famous Hyatt Regency walkway.
I second that. As a mechanical engineer, we needed to learn about public works and prior disasters that has happened when there is lack of rigor or otherwise oversight, including Tacoma bridge and Hyatt Regency walkway.
i covered them twice even. once as a mechE undergrad, and again in business school. the former primarily focused on the engineering dynamics and ethics, and the latter primarily on the organizational behavior and decision-making failures.
We covered software-induced disasters in my CS courses. This isn’t standard, which explains a lot about our profession.
My two favorite examples were:
The Therac-25 — it’s just frontend GUI code. Why test it? What could go wrong?
The Siberian gas pipeline explosion of ‘82 — not technically an accident, but it shows the problem with testing untrustworthy code to correctness. It was also the biggest non-nuclear man-made explosion, at least at the time.
The Russians had stolen some pipeline schematics from US companies. The theft was discovered before they stole the control software. Instead of stopping the software from being stolen, US intelligence modified it so an integer would overflow after a year (or two) of operation. The Russian economy would be ruined if the pipeline wasn’t operational in less time than it would take the bug to trigger, so it wouldn’t show up in testing.
When it triggered, it slammed a bunch of valves shut, causing multiple parts of the network to explode at the same time.
The US military’s seismologists detected it, and thought the Russians had detonated a new type of nuclear weapon. The military was going to escalate until the intelligence service told them they were responsible for the blast.
Also London's "Wobbly Bridge", which closed after its first day due to resonance that caused severe swaying. Two years of remedial work, installing dozens of energy-absorbing dampeners, solved the problem.
Interestingly, the Golden Gate Bridge is a sister bridge to the tacoma narrows bridge. After the bridge failed, they added reinforcements to the golden gate bridge to attempt to fix the issue.
Excuse me??? What an uncharitable interpretation of my comment.
I highlighted an example of a more catastrophic mistake, familiar to engineers, which was apparently forgotten in this case. Bridges are resonant structures; this is 100% predictable through modeling but that was not done.
Sibling comments point out the Hyatt walkway (news to me, I only took first year mech eng but learned about "galloping Gertie" in elementary school because it was a local and recent catastrophe). Other comments note that the construction crew must have noticed. That this was not escalated points to a communication breakdown similar to the root cause of the Hyatt walkway.
The second law of thermodynamics says that the energy of reducing the wind's speed has to go somewhere. It's either going to push the bridge around, make noise by generating vibration, generate electricity as in a wind turbine, or some combination of the three.
Does anyone know if they are planning on removing the slats? Maybe if they randomly changed the spacing of the slats if it would alleviate the problem ?
What's resonating? If the slats themselves are resonating, spacing them differently won't help much. Then again, if it is the slats would a horizontal brace running along the middle of the slats dampen or eliminate the resonance?
Dampers are probably only solution that doesn't involve rebuilding it. I haven't seen a great photo, but one of the videos seems to show the rails are square tubing...so could be vortex shedding?
Running a brace might not be a bad idea, but i could imagine that it might just double the octave, and make it a bit quieter
if damping weight work I could see a crowd sourced solution, a lot of people in the area could get some gorilla glue and a bucket of pebble and glue them on the slats.
Good point, it could be that they are vibrating like reeds. Bracing could help in that case. or could they attach weights to each one to change the resonant behavior ? It would be interesting to get a high speed video of one to see.
I like how this article and lots of people's tweets mention '2020.' As if 2021 is going to be any better and things won't just remain permanently horrible! Have a nice day!
The expressway I-5 bridge in Seattle is notoriously loud and can be heard for miles around. Interestingly, the sound from the busy topmost lane doesn't seem to make it to the ground. You can verify this during the brief pause when the express lane changes directions. I believe the traffic noise from the express-lane is reflecting off the underside of the upper lane. Seems like a diffusing layer on the underside of the upper lane would reduce the sound getting to the city below.
Reminds me of Google’s old Crittenden Lane buildings. The buildings have exterior metal vertical slats over windows for shade control. They sing when it’s windy.
I'm glad the tones produced are a whole step apart instead of a half step or something smaller. I wonder if they took that into account in the design; it always drives me nuts when two neighboring beeping electric turn-styles beep in just slightly different tones.
We just live with a very loud sound at our house. Run water for any reason. When you stop, some 0-15 seconds later an enormous sound reverberates thru the house. Plumber says its 'water pipes growing or shrinking, rubbing against the straps'. But it goes on for 10-30 seconds. No water pipe in the world moves that long/that much?
Online I see that described as a 'hammering sound'. Not our problem. We have an extended thrumming that lasts for many seconds. And it can be delayed from the event by seconds. Is that definitely the same thing?
If its water hammer (as it sounds like it is)-- it can fatigue joints and valves and cause leaks over time. Water hammer can be fixed by putting hammer arresters at the right locations.
Water hammer is cause by the inertia of flowing water. Water flows, it stops. Bang.
It might be in your case that water hammer is triggering an oscillation in ... something. A valve, pipes that arn't strapped down?
There could be a dead end in the system (essentially a hammer arrester) that is full of air which water is sloshing into and shaking in the process.
What I think I'd try to do is isolate the cause. E.g. if you turn off the service valve into the house can you trigger it by opening and closing the hydrant?
Maybe you are triggering a _pump_ upstream from you?
In any case, if pipes are shaking or the pressure is obviously spiking then it increases the risk of failure... so it's not something that I'd personally want to ignore.
IANAPlumber but the "water hammer" effect is usually very immediate and short. It literally sounds like a hammer hitting something.
What you're describing might be along the same principles but much larger, or it might be something else, but in any event it sounds serious. (No pun intended.)
Get a second opinion before a pipe bursts or comes loose, eh? If by "the outside hydrant" you mean a fire hydrant then I would call the city too.
I've not been able to identify any section of pipe where I feel vibration. Yet the sound permeates the house.
Live on an acreage, and the outside hydrant is mine by the garden. Right by the well, which is a tube extending 111' straight down to a submersible pump.
In the utility room, the water service comes into a pressure tank. We just replaced the tank, and the sound began after that. The plumber insisted it was unrelated. Maybe a relief valve there would help...just a guess.
Weird. I'm really not a plumber, so I feel silly offering my opinion, but what the heck, it's the internet, right?
If there's no vibration that you can feel then it's probably alright. Flutes don't fall apart from their own sound. But we're talking about your plumbing here, where a failure can be expensive and inconvenient, so "probably" isn't that reassuring. It's just not supposed to be doing that.
> We just replaced the tank, and the sound began after that. The plumber insisted it was unrelated.
It's not impossible (that they're unrelated) but that sounds to me like the obvious culprit, eh?
Sound perception is extremely complex and nuanced. The brain can tune out both specific frequencies and baseline shift while the ears are more sensitive to some frequencies over others. This sound is fairly pure and doesn’t really overlap with other artificially created sounds you’d encounter about the city, but I’m not an expert!
From your article:
"The wind retrofit project is designed to make the Bridge more aerodynamic under high wind conditions and is necessary to ensure the safety and structural integrity of the Bridge for generations to come,” Cosulich-Schwartz said."
This statement doesn't agree with the video's rationale for updating the railings. I'm guessing the new suicide net increased the wind loading, so the handrail had to be modified to reduce its wind loading. Without the suicide net project, I doubt the handrails would be changed. But the suicide net project is contentious politically, so they cannot admit this.
The new handrail uses long, unsupported plates. The old handrail was far more rigid:
The net is 20 feet below the bridge, so there's quite the adrenaline rush just falling to the net. After getting caught by the net, you're subject to high winds and quite the view, straight down, of the ocean below. Jumping a second time would be mechanically possible, but would not be easy for a human to do. Without the net, it's a quick hop over the side so having the net allows bridge workers critical time to go and respond to any attempts (which is about one every-other-day).
> “We knew going into the handrail replacement that the bridge would sing during exceptionally high winds from the west, as we saw yesterday. We are pleased to see the new railing is allowing wind to flow more smoothly across the bridge.”
I wonder if they will now need to install thousands of rubber vibration dampeners wedged between the slats.. like large versions of tennis racket string dampeners.. if that is possible to do without catching too much of the wind trying to pass through. Maybe only on every other slat, or every three slats, could reduce the noise at least somewhat.
So then someone would need to custom manufacturer all of those pieces of rubber and then they would all need to be jammed in there. But then the weather would probably degrade then over time.
I just wonder how many millions are going to be spent on mitigating this.
I don't live in SF but have visited a few times. I would be incredibly angry if someone arbitrarily decided to add a whole bunch of noise into my environment for no good reason. However "interesting" the noise may be to some people, having to deal with it in my daily life would be awful! I cannot comprehend how a person or group could be allowed do something like that.
This sounds exactly like the audio synthesis I did for a recent generative sound app. I didn't know too much so a very high q band pass filter over brown noise did the trick. Do that over several voices (not necessarily harmonic) and you get something similar. Check it out: https://apps.apple.com/us/app/night-shapes/id1490540845
With the clouds in the background in the video and the shape of the installation, my first thought on how to describe it would be a tornado rather than a tree. Maybe growing up in Tornado Alley predispositions me that way. I could see it as some sort of storm warning setup, steampunk style.
I'd assume that the engineers would have performed some form of stress tests for these installations that were actually meant to afford wind resistance and that the noise should have been noticed. Does anyone know how these conditions are tested in a simulated large structural engineering lab?
Makes me almost happy for my hearing loss from attending a Jack White concert in a tiny bar where he maxed out the sound system. Although that’s probably worse off.
I wonder what the space is in between the slats, or more precisely, the period. Working out what pitch this is, and a bit of $v=f\lambda$ might tell us which way the wind is blowing.
I should probably know this, but mechanical design packages include thermal modeling and fluid dynamics modeling. How about modeling for resonating in wind?
Given it makes sound, it vibrates at high frequency. I've troubles understanding why a vibrating bridge is "better for structural integrity". I remember some of these in the past which broke
It took me and my neighbours a month to find the source of a hum that was resonating with our windows. It was torture, with midnight walks and lurking around potential sources, mapping nearby industrial sites, and questioning our sanity, while our windows were vibrating without a stop. We were very lucky to track it down to a badly installed air conditioning vent 200 m away.
https://en.wikipedia.org/wiki/The_Hum