How to make annoying alarms

by on December 23, 2016 at 1:07 am in Law, Medicine, Science | Permalink

The faster an alarm goes, the more urgent it tends to sound. And in terms of pitch, alarms start high. Most adults can hear sounds between 20 Hz and 20,000 Hz—Baldwin uses 1,000 Hz as a base frequency, which is at the bottom of the range of human speech. Above 20,000 Hz, she says, an alarm “starts sounding not really urgent, but like a squeak.”

Harmonics are also important. To be perceived as urgent, an alarm needs to have two or more notes rather than being a pure tone, “otherwise it can sound almost angelic and soothing,” says Baldwin. “It needs to be more complex and kind of harsh.” An example of this harshness is the alarm sound that plays on TVs across the U.S. as part of the Emergency Alert System. The discordant noise is synonymous with impending doom.

After the alarm designers create a range of sounds in the lab, says Baldwin, they will test the annoyance factor of these sounds in a process called “psychophysical matching, or psychophysical ratings.” Yes, this involves subjecting human beings to a bunch of irritating sounds. Participants determine how annoying the sounds are by sorting them into categories ranking them on a scale of one to 100. 

Then there’s more testing. “If it’s a medical alarm, for instance, we’ll start using that sound and then we’ll maybe measure people’s physiological response to it—does their heart rate go up, does their skin conductance level go down, what happens to their brain activity,” says Baldwin. Skin conductance measures how much the sound affects the body—skin gets better at conducting electricity when the body is physiologically aroused.

An effective audio alarm is one in which the annoyance factor and perceived urgency of the sound is matched to the hazard level—a soft little chime for the fridge door, say, and a “BREHHHHK BREHHHHK BREHHHHK” for a plane in a tailspin. “We want it to be detectable, so to get your attention, but for you to recognize what it means right away,” says Baldwin.

It turns out this is a problem in hospitals:

In hospitals in particular, there are “so many nuisance alarms going off all the time, that people—nurses, doctors—just tune them out,” says Baldwin. “They don’t even hear them anymore.” The statistics say that most of these alarms are not indications of peril. A 2012 review of medical audio alarms found that in one intensive therapy unit, “of 1455 soundings of alarms, only eight were associated with potentially life-threatening problems.”

Here is the full piece, from the excellent Atlas Obscura, and for the pointer I thank Torsten Kehler.

1 mbka December 23, 2016 at 5:00 am

Interesting tidbit but:
– The 20-20000 Hz meme sounds good, is easy to remember, and applies at best to young people. Adults typically don’t have that range, especially in the higher frequencies. Even then, the extreme ends of the frequency band are only heard at extreme loudness levels, see equal loudness curves, for example here I can hear between 40-14000 Hz at reasonable loudness levels.
– 1000 Hz is emphatically not the bottom range of human speech. Example, It is one of two low points in hearing threshold. At 3000 Hz the threshold is even lower than at 1000 Hz. So 1000 Hz or 3000 Hz are good starting points to make maximum audibility of a signal.

2 brone December 23, 2016 at 6:28 pm

Ms Baldwin may have an advantage, being female, since women tend to suffer less from age-related hearing degradation.

But 20KHz is still quite high. The Mosquito plays a 17.5KHz sound that is supposed to be inaudible to the majority of adults:

3 So Much For Subtlety December 23, 2016 at 5:30 am

In hospitals in particular, there are “so many nuisance alarms going off all the time, that people—nurses, doctors—just tune them out,” says Baldwin. “They don’t even hear them anymore.” The statistics say that most of these alarms are not indications of peril. A 2012 review of medical audio alarms found that in one intensive therapy unit, “of 1455 soundings of alarms, only eight were associated with potentially life-threatening problems.”

I am not getting this story. So there has been a proliferation of alarms, not all of which are as urgent as they sound. An alarm inflation. So they will make some alarms more annoying. But won’t that just lead to an arms race? That is, the other alarms will become just as annoying – if the makers didn’t think their alarm was important, it wouldn’t be an alarm.

How does it improve things to be exposed to 1455 extremely annoying alarms? What happens when they become so annoying the doctors can’t tune them out?

4 dan1111 December 23, 2016 at 6:09 am

I think the point is that, yes, this proliferation of alarms is bad.

But if you are making a new device that needs to make an alarm, for an actually critical event, the only thing you can really do about it is make your alarm louder and more annoying. And device makers also are probably incentivized to add unnecessary alarms, through things like device approval processes and the fear of litigation. It does tend to lead to an alarms race.

This is some sort of tragedy-of-the-commons-like thing. In isolation, each alarm appears beneficial. Devices tend to be evaluated in isolation. But in combination, the effect is detrimental.

5 JWatts December 23, 2016 at 10:20 am

I’ve been in several hospital rooms recently where the nurses have problems managing the alarms. There clearly needs to be a better defined and followed standard. Only critical alarms should actually be audible.

6 Mark Thorson December 23, 2016 at 12:16 pm

I think the solution has to be a standard for funneling all of the alarms into one channel, so there would be one source of audible alarms and one place to look to see what it is. It would be like a status board on the wall, so you’d just look up there and see “Heart rate alarm, bed 4” or something like that. If there’s multiple alerts, you hear one alarm but the board would show a red light for each machine indicating an alert.

This could be introduced at the same time as the solution of another crisis — the proliferation of cables, especially in operating rooms. You’ve got a ridiculous number of cables running everywhere. Everything should be converted to short-range wireless, like Bluetooth.

A big part of the problem is that many of the vendors of medical instruments are small companies, and many of those only produce one type of instrument. Asking them to adopt a wireless capability and communications protocol often would mean hiring a new engineer, which would be a big burden for many of these companies. Also, an updated product would have to go through FDA approval again, which is very costly. I would expect the industry to resist such a move until they’re forced to do it.

7 Daniel Weber December 27, 2016 at 10:44 am

Cockpit design in an aircraft is probably the best model. You still have a bunch of vendors that are all pushing their own stuff out, but there is someone in charge (plane assembler) who forces there to be standards for just when something is allowed to alarm, or flash, or even shine the color red.

8 John de Rivaz December 23, 2016 at 5:59 am

Surely evolution has provided the answer to that — a baby yelling. The frequency band of the fundamentals and amplitude modulation of the sound fit exactly.

I do find it interesting and inexplicable that a person snoring is irritation but a cat purring is soothing, yet the sounds aren’t that different.

9 dan1111 December 23, 2016 at 6:10 am

Volume matters. I bet it would be really hard to fall a sleep with a cat purring right next to your ear.

10 dan1111 December 23, 2016 at 6:12 am

There is possibly also a psychological aspect, though. Once you believe something is annoying and expect it to keep you awake, that tends to be self-perpetuating, because actually the anxiety about it keeps you awake.

11 Thiago Ribeiro December 23, 2016 at 6:28 am

Brazilian alarms are among the best and the cheapeast in the world.

12 dan1111 December 23, 2016 at 6:34 am

And among the most necessary.

13 Thiago Ribeiro December 23, 2016 at 7:35 am

There is some exaggeration, I think.

14 dan1111 December 23, 2016 at 7:53 am

Sorry, couldn’t resist. I have nothing against Brazil.

15 Thiago Ribeiro December 23, 2016 at 9:32 am

I will tell you what I told a Japanese girl who was complaining about crime rates in Brazil: “You are much more safer from being robbed, tortured, raped and killed in Brazil than a Korean woman ever was under the brutal Fascist Japanese occupation. Brazil is the only country that has never commited war crimes. Violence is antithetical to the Brazilian character. The French, the English and the Russians killed their kings, were sent our last Emperor to Paris. Other countries fought war to abolish slavery, we abolished slavery peacefully because it was the right thing to do”

16 JWatts December 23, 2016 at 11:11 am

“You are much more safer from being robbed, tortured, raped and killed in Brazil than a Korean woman ever was under the brutal Fascist Japanese occupation.”

Well it’s great to hear that Brazil manages to hurdle that bar.

17 Thiago Ribeiro December 23, 2016 at 12:12 pm

The point is, we have been slandered for too long and I won’t let Fascists lecture me about proper behavior. If shedoesn’t like Brazil, she can go back to Cipan Guó. We have every reason to be proud of our country and its towering achievements. As an old Brazilian song has it, “Future belongs to us, we’re just beginning.”

18 JWatts December 23, 2016 at 2:07 pm

Well, I think other people have some other impressions about Brazil than you seem to be espousing. This article came out this morning:

“2016 Was Awful for Brazil and 2017 Doesn’t Look Much Better

Few Brazilians will mourn the passing of 2016. The president was impeached, a vast corruption scandal dominated the headlines day after day and a devastating recession – the worst on record – crushed the hopes of millions.”

That doesn’t sound very positive. Are you sure your POV isn’t a bit rosy?

19 Thiago Ribeiro December 23, 2016 at 3:37 pm

Oh, I still remember that no athlete was supposed to survive the mortal Olympic Games of Brazil or that the World Cup games would be played with human heads instead of balls. All we learned from those sports events is that Brazilian criminals force American swimmers to forge crimes. There was also the Brazilian epidemics that were to destroy Mankind. Maybe it is time to tone down the anti-Brazilian propaganda. Seriously, guys, the Pravda called and they want their editorials back.

As for the corruption, the only atypical thing in 2016 is people being punished (the problem was so old and deep that a Brazilian minister said the construction firms were the ones designing the governent budget to suit their interests… he said it in the mid-1980s). Now, energetic measures have been taken. Two former Rio de Janeiro governors have beem arrested, the president was impeached, his replacement probably will be deposed, the House Speaker has been jailed, the President of Senate may be arrested any time now, top bankers and construction business CEOs have been jailed, half the country’s Congressmen a under investigation, a living terror has spread through the land. Sweeping the dirt under the rug is how you get Donald Trump and a desperate frightened populace who doesn’t believe in the system anymore. We, Brazilians, can look forward with unashakable faith in the Fatherland because we know we acted decisively to cut the snake’s head.

Also I have lived through more recessions and currency changes (I still remember when comic books had no prices on their covers because prices changed more than once a week… or a day) — and my father through more Constitutions — than you have teeth, so trust me when I say we shall overcome , some day. The fundamentals of our economy are strong, our land is generous and our people is brave, strong and intelligent. We shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe to assure the survival and the success of our country and its system. We shall fight with growing confidence and growing strength and in our righteous might we will win through to absolute victory. Make no mistake about that. Our Fatherland has faced much more dangerous threats and it has prevailed and it will prevail again. The same way our great-grandfathers prevailed at the swamps of Paraguay and our grandfathers stormed the beaches of Italy, we will conquer the economical problems that face our society. For all its flaws, the Brazilian state is mankind’s greatest achievement, an empire bigger than Rome’s. As a Brazilian anthem says, we are Greek in our glory and Roman in our virtue. Being Brazilian is glorious!

Our Fatherland is, obj

20 Thiago Ribeiro December 23, 2016 at 3:40 pm

* Our Fatherland is objectively great and, as a Brazilian anthem says, “From the Universe among Nations/ From the Universe among Nations/Shines brightly that of Brazil”. Let it shine, I say.

21 msgkings December 23, 2016 at 2:38 pm

dan1111 crushes it with the 6:34 comment. Shame he wimped out right after. I had nothing against Brazil either until Thiago showed up. Of course I really don’t have anything against Brazil, and Thiago is endlessly entertaining as a soft target.

22 Thiago Ribeiro December 23, 2016 at 3:42 pm

“I had nothing against Brazil either until Thiago showed up.”

“I am not a racist, but…”

23 Steve December 23, 2016 at 7:10 am

Here’s a video of a two-tone “Thunderbold” civil defense siren I remember hearing as a child. Many other towns had them. Have not heard a more ominous-sounding alarm since.

I look forward to hearing more alarms under the Trump presidency.

24 Thiago Ribeiro December 23, 2016 at 7:41 am

For only when our alarms are sufficient beyond doubt can we be certain beyond doubt that they will never be employed.

25 Troll me December 24, 2016 at 3:03 pm

We could try mandatory 3 cameras a room in any building, with cameras at every street corner, along with microwave pulse patterns to tell us everything is OK with that.

I bet there will not be many unsanctioned purse snatching after that. But the whole matter of having a seed of a thought to change things, and not being able to get much further than that in such a system, might make the whole thing a little counterproductive to what people actually want. (I assume that powerful people, in such regards, basically want the same things as the rest of us.)

26 mkt42 December 23, 2016 at 8:10 am

Interesting. Hawaii has, or at least had, sirens that made that exact same sound — except instead of tornado warnings, they were tsunami warnings.

Oregon’s coast had a network of tsunami alarms, but in the name of cost-cutting many towns are removing them!

27 Thiago Ribeiro December 23, 2016 at 9:37 am

Wouldn’t it be cheaper have a man yelling: “The Tsunami is coming, the Tsunami is coming!”? If it was good enough for the Fou ding Fathers, it should be good enough for Occupied West Idaho.

28 chuck martel December 23, 2016 at 7:36 am

Back-up alarms for heavy equipment are so common on construction sites that they’ve lost effectiveness. Suggestions to incorporate visuals to the alarms, flashing lights, for instance, fall on deaf ears. Alarms in this case are meant to satisfy insurance or OSHA requirements, not practical considerations of safety.

29 Troll me December 24, 2016 at 3:07 pm

Maybe better training instead of ever more monitors and sensors of our every move?

So … maybe a few steel beams will kill a few more people than the “full Orwell solution”. Personally, I’m quite OK with risking their lives for my security. But at the same time, I think they’d rather it that way too.

30 Chandrasekhar Ramakrishnan December 23, 2016 at 8:23 am

The Percussionist and sound artist Max Neuhaus did interesting work on developing improved sirens/sounds for emergency vehicles.

31 harpersnotes December 23, 2016 at 9:23 am

Signal filtering technological hacks? Individuals in hospital-like environments might begin wearing high-end noise-cancellation headphones plugged into their smartphone digital personal assistants. People might adjust settings on their digital personal assistants so that they can quickly send messages by vocalizing according to predesignated word sequences like ‘Siri tell Bob …’ etc. Then management would likely try to reduce the use of such hacks by setting rules and also by trying to increase compliance with the new rules by jaw-boning down the excess use of alarms (‘please be considerate of your more highly noise-sensitive co-workers…’)

32 Todd K December 23, 2016 at 10:03 am

“…and a “BREHHHHK BREHHHHK BREHHHHK” for a plane in a tailspin. “We want it to be detectable, so to get your attention, but for you to recognize what it means right away,” says Baldwin.”

To get your attention, it would be much more useful to have an alarm on a plane with a calm voice of Stephen Hawking repeating: “You’re all going to die You’re all going to die You’re all going to die” as that would capture their attention but have them remain calm at the same time.

Maybe a few bugs still need to be worked out. Just an idea.

33 John December 23, 2016 at 10:16 am
34 John Mansfield December 23, 2016 at 4:07 pm

Maintaining a distinction between alarm and alert would be useful. If someone is fully occupied with monitoring a system, then receiving alerts every so often of something out of spec is part of the monitoring just like keeping an eye on gauges and readouts. Isn’t that the point of an ICU, that the patients need to be constantly monitored? Do the little “check this out” beeps all sound the same as the “someone’s going to die” claxons?

35 KevinH December 24, 2016 at 11:29 am

The person writing this seems to know very little about sound.

1kHz isn’t “at the bottom of the range of human speech” Most speech has a fundamental frequency of 100-250 Hz. For reference middle C has a frequency of 261 Hz.

Also, Harmonics are a natural tendency of ALL sounds, and are unrelated to how many notes are played. A two note sound would comprise 2 different harmonic stacks. Most natural sounds are 1/f meaning that the power of the sound drops by half for each rising harmonic. The relative strength of various harmonics can give character to a sound, and is what differentiates the sound of say, a violin vs a piano, and is what distinguishes between vowels such as ‘a’ vs ‘i’.

As many sounds have base frequencies around 250Hz, and these harmonics give character to the sounds there is a lot of information around 1k – 5k Hz about sounds. This is probably why we have increased sensitivity in that region.

source: PhD in auditory neuroscience

36 Troll me December 24, 2016 at 3:15 pm

Coursera occasionally has courses which teach about programming related to these things. From the perspective of sound engineering for music.

37 Tom Bri December 26, 2016 at 5:06 am

I’m a cardiac nurse. We have endless minor alarms going off, but the really important ones are much louder and immediately identifiable. If someone drops into a deadly heart rhythm, what we call ‘the bat phone’ starts ringing, very loudly, and everyone jumps and runs to that room.

The big problem is that the minor alarms mostly ring inside the patient’s room, both annoying/awakening the patient, and being easily ignorable by the staff. We need alarms to ring outside the room, much like the call buttons work. When a patient wants something, even just to get his pillow fluffed, he pushes a button and it rings a soft alarm in the nurse’s station. Whoever is at the desk answers and responds (quickly or slowly!). I’d like to see our IV pump alarms set up that way, saving a lot of hassle for us, and annoyance for the patient.

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