
Mercedes-Benz pre-safe sound - melenaboija
https://www.mercedesbenzofnatick.com/new-features-mercedes-benz-comand-system.htm
======
taylorlapeyre
I lost most of my hearing in my left ear in a head-on collision with a drunk
driver. No other injuries. The audiologist said that my eardrum was in the
kind of state you usually only see in battlefields from exposure to large
explosions.

People are always surprised when I tell them this was my only injury, and as a
result I've always wondered how common this type of injury is with vehicle
collisions. This is the first thing I've seen which makes me believe that it's
a lot more common than people suspect.

Very cool! I hope this is taken up by other brands as well.

~~~
ChickeNES
There was a blogpost I read a few years back written by someone who damaged
their hearing after dropping a porcelain toilet lid. They actually ran some
back-of-the-envelope calculations to estimate the decibel level, I recall it
being shockingly high.

~~~
coke12
There was a pretty good HN comment thread about it:
[https://news.ycombinator.com/item?id=16723099](https://news.ycombinator.com/item?id=16723099)

From the linked thread:

""" 5\. The stupid toilet bowl lid only fell about 8 inches. How could it
damage my hearing so badly? I looked up the speed of sound in ceramic, divided
by the length of the toilet bowl lid (and divided by 2 since the fundamental
vibration is a half wavelength). This predicts 3.5 kHz.

6\. This frequency is in the audible range. Using the short dimension of the
toilet bowl predicts another (higher) frequency. The toilet bowl lid probably
resonated at both those frequencies and their harmonics, putting all the
energy into just those specific wavelengths.

7\. The toilet bowl lid was not chipped or damaged, so the impact energy went
mainly into sound (& internal heat) Maybe like half the impact energy went
into sound energy. This lid was concave up like an antenna, near my face when
it hit, focusing the energy into my face.

8\. The energy travels into your inner ear and the cochlea. The pressure wave
is strongest at some distance down the cochlea depending on frequency. Since
the toilet bowl lid put all the energy into SPECIFIC FREQUENCIES, it was
concentrated onto specific spots in the cochlea.

9\. Apparently, this concentration of energy was enough to damage the hairs --
to bend them over like trampled grass -- and I was concerned it could be
permanent. My hearing was only slightly better the next morning. It was like
everybody was still talking at me through kazoos. """

Fascinating. Be careful around dropping shatter-proof ceramics, I suppose!

~~~
Cerium
Be careful dropping glass bottles into recycling bins too; they pose nearly
the same problem - they don't usually shatter and the sound escapes the bin
upwards towards you.

~~~
mehrdadn
Why isn't this taught to everyone at a young age? I had no idea this could
happen and it kind of terrifies me that I can lose my hearing so easily like
this without having any clue.

~~~
mikestew
Then go buy the toilet lids that don’t drop with the acceleration of gravity,
i. e., “soft close”. Hearing loss or not, I don’t want to hear anyone dropping
the toilet lid in the middle of the night.

~~~
morsch
The culprit was actually a _lid on the tank_. I've never seen a toilet lid,
soft close or not, that doesn't have plastic pieces that prevent full direct
contact between the lid and the part below it. They'll deform under pressure,
taking the noise level down from unbearable to just loud.

~~~
mikestew
Yeah, I saw that it was the lid after I posted. In fact, I even _remember_ the
original post, and at the time thought, "huh, never even thought of that".
Welcome to middle age, where a _lot_ of stuff starts to occur to you after the
fact. :-|

------
hbosch
I just want to say that this is exactly the type of thoughtfulness, design,
engineering and research that justifies the price difference in something like
a Mercedes and something like a Honda. There are _so many_ small triumphs like
this in class-leading, high-end vehicle manufacturers that go unnoticed and
unsung and allow people with 2019 Accords to say things like "why would I pay
$45,000 for _that_ when I get better auto-steering for half the price?".

Certainly there are subtleties to high end cars like road feel, steering,
throttle feedback, and ergonomics that are only apparent to "car people" and
thus work the premium versus something that is more "point A to point B". I
applaud Mercedes for not only putting the effort into deploying a feature like
this, but also for marketing it.

~~~
kemitchell
How about the difference in long-term cost of ownership, serviceability, and
overall reliability?

It's certainly one kind of car person that wants the latest and greatest
nearly all the time. Some like to patronize particular auto makers, like
fashionistas patronize fashion houses. It's quite another, equally valid kind
of car person to take used examples of far simpler, utterly reliable cars and
add suspension, brakes, forced induction, tuning, and so on far beyond what
any manufacturer fits on any mass-market vehicle. They patronize component
makers, often race- or restoration- oriented.

As for the non-enthusiasts, if you plan to lease a vehicle or trade it in
every few years like clockwork, the eventual cost of added complexity might
never affect you, apart from resale value. But the virtue of combining good
mechanical QA with simplicity and serviceability is also much unsung, and
cheaper, not more expensive.

~~~
bluetomcat
> How about the difference in long-term cost of ownership, serviceability, and
> overall reliability?

Long-term owner of a 2004 Mercedes W211 E320 CDI in Europe, with 420k
kilometers on the clock.

The inline 6-cylinder engine and the 5-speed auto transmission still work
buttery smooth and the car pulls like a train without ever smoking. No
interventions have ever been done to the engine and trans, apart from changing
consumables on-time. The car still has a very solid feel to it, without any
interior rattles and squeaks, with very few wear-and-tear signs on the
interior. The original paint is still gleaming. The thickness of the paint and
the metal is easily noticeable. A Honda of the same age and miles would
probably still run, but will feel sub-par in most of these respects.

The car has a lot of electronic systems controlled by dedicated electronic
units, the most notable of which is the brake-by-wire SBC system. It had been
causing problems in early production, but the issue was fixed and that unit
was replaced under warranty on almost all cars. It was a big reputation hit
for Mercedes, though. That system was very innovative in the sense that it
provides a common architecture for implementing traction control, ABS, brake-
hold, etc.

So far, none of these systems have failed on my car, apart from the need to
replace a few failed sensors for which I got warnings on the dashboard and
were diagnosed easily while in the repair shop.

~~~
dvdbloc
Just wanted to share that I am a proud owner of a 2005 W211 E320 as well, gas
however. 235k miles on the clock and it still starts up with the same 2 cranks
and woosh as it did new and pulls on the highway just fine. Definitely a
quality vehicle that has not only held up but hardly degraded since new.

~~~
benjaminsuch
I once talked to a taxi/cab driver about, why (in germany) almost every
taxi/cab are a Mercedes. He said, that is is because of the insane durability
of Mercedes cars. Plus it's easier for them to maintain them, since even for
older cars there are plenty of repair parts (is that the correct term?)
available.

~~~
kemitchell
Mercedes in Germany tend to be made in Germany, and there's a network effect
in having so many around. I imagine Merc spares availability in Germany is a
bit like Ford or Chevy parts availability in the US. With cabs, it's not a
question of whether there will be issues, but when, and for how much. Here in
the US, cabs routinely do full engine swaps to stay on the road. So many US
fleets, like police departments, favor American cars.

------
ascar
Why not link to the source directly at Mercedes [1]?

The website has only added marketing to the information available in the video
from the original site.

I honestly thought this is satire until I saw it from the source, but this is
actually pretty cool.

[1] [https://www.mercedes-benz.com/en/next/connectivity/pre-
safe-...](https://www.mercedes-benz.com/en/next/connectivity/pre-safe-sound-
playing-pink-noise-in-the-split-second-before-impact/)

~~~
fastball
I like the OP better, to be honest.

Your link is weirdly formatted on my machine to the point it looks broken.

Also I prefer reading text to watching a video.

------
raldi
I wish fire alarms did this for half a second before blasting your tympanic
membrane with an ear-splitting noise. Residential ones are bad enough, but the
ones in offices are the worst.

~~~
tempestn
That's a good idea! I bet if someone were to develop a residential smoke
detector that did that it would sell well. (Especially if it had other
compelling features like a 10-year battery.)

~~~
abfan1127
FYI - The 9V Lithium batteries last that long.

[https://www.amazon.com/Energizer-LA522SBP-Lithium-Battery-
De...](https://www.amazon.com/Energizer-LA522SBP-Lithium-Battery-
Detectors/dp/B003VKOEBM)

~~~
tempestn
Good to know! We bought a few with integrated 10-year batteries from Home
Depot a few years back, but I didn't realize you could get regular lithium 9Vs
that last that long in a smoke detector now.

~~~
moftz
You should replace the smoke detector after 10 years anyway so buying the
disposable ones is probably safer.

~~~
NikkiA
!! even the hard-wired ones are supposed to be replaced after 10 years, and
_new_ hard-wired ones will automatically brick themselves after the 10 years
is up !!

~~~
tempestn
For anyone reading this wondering how that's safe, I believe they make noise
regularly once they reach this state, to encourage you to replace them, rather
than just silently failing to operate!

~~~
NikkiA
Yep, blip every 30 seconds for 6 weeks, until they go silent.

It'll drive you nuts, especially if your handy builder put them in out-of-
reach places.

------
CaliforniaKarl
I think this should be marked [2015], as the video included on the site was
uploaded in 2015.

But still, this is really cool! I also didn't know that the ear has a "self-
defense" mechanism against loud noise. I wonder how that mechanism interacts
with things like headphone audio being played at high volumes. Does the
mechanism eventually wear out? How does that affect people who do sound
effects/mixing/mastering for a living?

~~~
outworlder
> Does the mechanism eventually wear out?

I hope not, because I have been able to control the muscle voluntarily and it
is still works after almost four decades.

It doesn't go off by itself all the time though. It's more for sudden loud
noise, I don't think it works at all for sustained loud noises.

~~~
MrEldritch
>I hope not, because I have been able to control the muscle voluntarily and it
is still works after almost four decades.

Oh, is _that_ how the brain rumblies thingy works? Huh, I never realized most
people couldn't do that.

~~~
tmacro
I realized it was rare, but I've never been able to explain what I'm doing to
other people. Now I finally know!

~~~
nsxwolf
Whoah! I thought everyone could do this!

------
hirundo
I'm guessing an engineer named it the German equivalent of "pre-crash" sound,
then someone in marketing decided that "pre-safe" sounds better. It may be
better to call it "foreplay" sound, since if you ever hear it you're probably
screwed.

~~~
kbutler
Some technical disciplines use "safe" as a transitive verb meaning "to make it
safe", either from damage or from damaging other things.

I've seen it most often in rocketry contexts - you "safe the rocket" in an
aborted launch scenario so it won't go off accidentally, etc.

    
    
      "It is a good idea to add a safety release valve to your launcher. Sometimes it is important to abort a launch and safe the rocket after it has been pressurised." http://www.aircommandrockets.com/rocket_launcher.htm (Google "safe the rocket" for occasional other examples.)  
    

So the PRE-SAFE sound means the sound is to "safe your ears" before the crash,
making them safe from damage.

~~~
Dylan16807
But for that definition it's not "pre" anything. It's either a safing sound,
or a pre-collision sound.

~~~
kbutler
The event is the collision.

It's safing in advance of the event (pre-safe), rather than after the event
(post-safe), which would be too late.

------
jedberg
The Mercedes is known for being more expensive than most, but in most cases,
it's worth it, not only for the luxury, but for the extreme attention to
detail they put into safety.

For example, when you get into one, it will adjust the tension of the seatbelt
automatically to be ideal for each passenger. And of course this pink noise.
And a ton of other little things that cost extra that most people will never
notice.

There's a reason the Mercedes is always at or near the top of any vehicle
safety list.

~~~
nradov
Unfortunately they don't devote any attention to longevity or serviceability.
But yes the safety features are excellent.

~~~
ascar
Mercedes is actually known for their engine longevity, reliability and
serviceability.

Yes they have more issues with technology than other cars, but that's because
they use more and newer technology than cheaper brands. [1]

[1] [https://www.osv.ltd.uk/are-mercedes-benz-
reliable/](https://www.osv.ltd.uk/are-mercedes-benz-reliable/)

~~~
pryce
I would find this more compelling if i hadn't had a Mercedes written off
because of their "smart" technology choices.

Apparently with their vehicles (in this case a C180/2004) the tensioner is
power-dependent and requires the vehicle to be used somewhat frequently to
work at all. This means that simply by not using the car for 4-5 months, my
dad returning to it and turning it on for < 3 seconds resulted in the motor
starting with the tensioner not working, resulting in timing chain failure
which irreparably damaged the valves and motor to the extent the vehicle was
written off.

I don't have much automotive expertise by any means, but my understanding is
that tensioner design in other makes of car generally do not experience
critical failure when presented with "being used seldomly".

~~~
leetcrew
it's disappointing that the tensioner of all things would fail in that
situation, but long intervals between use is a problem for all cars.

if your dad regularly lets a car sit for five months without driving it, he's
going to have a lot of car troubles. ought to at least take it out a couple
times a month, just for 20-30 minutes (ie, long enough to get fully warmed
up).

------
JshWright
It's crazy how fast a car deals with a collision. In the event of an actual
crash, the car is _done_ processing the event and deploying all safety
measures (airbags, seatbelt pretensioners, etc) before your body even begins
to recognize the sensations of impact.

~~~
gmueckl
Not only that. Modern safety systems distinguish between different types of
crashes and compute e.g. the optimal time to deploy the relevant airbags while
the crash is happening. Supposedly, some implementations rely on piezo
crystals embedded into the car frame to measure how the car is being deformed
during the collision.

------
julianwachholz
Mercedes did a small YouTube series on this together with Veritasium. Very
interesting material.

[https://www.youtube.com/watch?v=82BRWm4SGL8](https://www.youtube.com/watch?v=82BRWm4SGL8)

------
emptybits
> "PRE-SAFE® Sound is activated if your vehicle detects that a collision is
> unavoidable"

See also: Peril Sensitive Sunglasses™

~~~
GrifMD
Joo Janta 200 Super-Chromatic Peril Sensitive Sunglasses

------
Havoc
Given that manufacturers are thinking seriously about reducing road death to
zero (well in survivable speed scenarios) [1] I guess looking at secondary
effects is the next step

[1][https://www.extremetech.com/extreme/287046-why-volvos-
cappin...](https://www.extremetech.com/extreme/287046-why-volvos-capping-top-
speed-at-112-mph-the-elusive-quest-for-zero-deaths)

------
sravfeyn
[https://en.wikipedia.org/wiki/Acoustic_reflex](https://en.wikipedia.org/wiki/Acoustic_reflex)
for people interested in 'stapedius reflex' that the article talks about.

------
blauditore
This sounds like it's something new, but I thought Mercedes had been doing
this for a long time already (read about it some years ago).

------
gnicholas
FYI, the pink noise sample in the video played back at 80 dB on my MBP (2017,
13") when I set the volume to max. I used an iPhone app to test the dB, and
when I put the mic about an inch from the speaker, it registered about 80 dB.

Back where I was sitting, it was much much lower, and definitely didn't affect
my hearing.

------
bookofjoe
Listen to it here: [https://www.autotrader.com/car-video/video-heres-what-
merced...](https://www.autotrader.com/car-video/video-heres-what-mercedes-
benzs-pre-safe-sound-sounds-action-281474979935876)

------
Zenst
Well, that may of finally explained such musical releases such as
[https://g.co/kgs/2SgdjX](https://g.co/kgs/2SgdjX) at least for the budget car
enthusiast market.

------
zmix
Some of the comments, just like PRE-SAFE SOUND, sound like an April Fool's
Joke. But, apparently, it isn't. Very interesting, indeed. I never would have
thought, that something like this might be an issue.

------
owenversteeg
Am I the only one who listened to the video and didn't have anything happen
with my tensor tympani? I can voluntarily control mine ("ear rumbling") so I
know what it would feel /sound like.

~~~
gnicholas
Unless you played it pretty loud, nothing should happen. What speakers did you
play it through, and at what volume?

~~~
owenversteeg
I played it at max volume on my P30 Pro next to my ears and didn't hear
anything... I'll try a more scientific test with an actual loudness
measurement later.

------
uasm
>
> "[https://www.mercedesbenzofnatick.com"](https://www.mercedesbenzofnatick.com")

That's one long domain name...

------
hindsightbias
Could this be used by the military to lessen combat injuries?

~~~
adamsea
Less combat would lessen combat injuries even more.

~~~
GhostVII
And lessening car crashes would help with injuries far more than pre-safe
sound. Unfortunately both are innevitable.

~~~
DagAgren
American combat injuries are anything but inevitable.

------
modzu
previous discussion:

[https://news.ycombinator.com/item?id=12813633](https://news.ycombinator.com/item?id=12813633)

------
azinman2
That’s pretty cool. Something non-obvious when we think about engineering
vehicle safety. Of course it only matters if you make it out ok :)

------
noisy_boy
Couldn't they come up with a more interesting name, say, "nudge-note"?

------
bobowzki
Now this is innovation! "Simple" and clever!

------
mrfusion
Is this why it doesn’t hurt your ears when you holler?

------
dsjoerg
I bought a Mercedes because of this tech.

------
trilila
“Mercedes-Benz is constantly at the forefront of automotive safety
technologies” - not really. Rear wheel drive, which is common in mb and bmw
cars are a real danger in winter. Volvo claims, and seems to be, a safer and
more at the forefront of safe driving choice.

~~~
snorrah
Modern day traction control systems have taken the majority of danger from
power oversteer out of cars.

But then the only advantage you get in winter driving comes from fitting tyres
(or tyre chains) appropriate to the conditions.

~~~
PaulHoule
I prefer front wheel drive but I was impressed with how a RWD Buick with
traction control handled in the winter.

------
jacobsenscott
I can't wait until there's an app to force this sound on via bluetooth on
every benz you drive past on the interstate :)

