13 ms·
Pre-Safe Sound: Playing ‘pink noise’ in the split second before impact (2015)
- codeulike 10y agoThe interesting bit: If an impending collision is detected that would be expected to produce a loud crash, the vehicle’s sound system plays a short interference signal. This causes the stapedius muscle in the ears to contract, which for a split second changes the link between the eardrum and the inner ear and so better protects it against high acoustic pressures. Most importantly, the reflex reduces the damage to hearing.
- xorgar831 10y agoHere's the sound: https://www.youtube.com/watch?v=bCOw5lisrIU&t=25s https://www.youtube.com/watch?v=bCOw5lisrIU&t=25s
- Swizec 10y agoI might be imagining this, but I could swear I felt my ears becoming "full". Sort of like tired of the noise and numbing down? It's hard to describe but it felt similar to being on an airplane for a long time where sound becomes kind of dull because of all the engine noise.
- 4ad 10y agoYou are not imagining it. (I guess it depends on the definition of "imagining", but that's philosophy.) It's definitely a real effect.
- dogma1138 10y agoYou aren't if you use headphones and play it at close to 80db the feeling is like when you put on the active bose noise canceling heaphones and turn them on. You feel a slight pressure on your ears which is what this intended to do.
- bane 10y agoYou might enjoy this site then, which has several different noise "colors", each has a different kind of effect or feeling. http://onlinetonegenerator.com/noise.html http://onlinetonegenerator.com/noise.html
- dingaling 10y agoIt had no discernable effect on me, in a fairly noisy domestic setting including a washing machine in the background. I was expecting it to be much more penetrating. Perhaps I've ruined my hearing after years of listening to shortwave white-noise.
- rosstex 10y agoI felt that as well.
- Angostura 10y agoI wonder if it as cool hypothesis that they decided to implement as a cheap bit of marketing, or whether the protective factor is actually evidence-based.
- oblio 10y agoThat's a bit cynical of you, isn't it? Also, would you say the same thing if it was another car company that did this?
- Angostura 10y ago> Also, would you say the same thing if it was another car company that did this? Why would I have something against Mercedes?
- pja 10y agoDid you actually read the article, or are you just here to snark on HN? Here, let me do your research for you. First link on a search for "stapedius reflex" is https://en.wikipedia.org/wiki/Acoustic_reflex https://en.wikipedia.org/wiki/Acoustic_reflex A quick search on Google Scholar for "acoustic reflex noise" turns up this paper from 1962 which states in the abstract that the acoustic reflex is more easily triggered by wide bandwidth noise than a single sinusoidal tone. http://scitation.aip.org/content/asa/journal/jasa/34/9B/10.1121/1.1918384 http://scitation.aip.org/content/asa/journal/jasa/34/9B/10.1... I think we can safely say that this work is pretty evidence based.
- Angostura 10y agoWell, I read the marketing piece, yes - but thank you for pointing me at the evidence. The level of 'snark' may have been influenced by me previously reading the Soylent story. Marketing masquerading as science is certainly a thing, though not in this case.
- fasteo 10y agoA friendly reminder: "a quick search on Google Scholar" is not research. That paper you mention is just a functional description of the "accoustic reflex". I don't think the parent comment was putting the existence of the "accoustic reflex noise" in doubt; rather, and I agree with him, it's its effectiveness to protect the driver in a car crash what is in doubt. The page makes a reference to a human trial in 2011. It would be great if they included a footnote with the reference to the actual paper.
- mannykannot 10y agoI have read somewhere of a click being played through tanks' crews headphones when the main gun is fired, for this reason. This was wrt 70s-era Soviet tanks.
- lordelph 10y agoMildly interesting: when I played the sample pink noise in the article, my dog went mental.
- rrmm 10y agoI wonder if that noise is going to be a major ptsd trigger for people involved in an accident afterwards. (Of course probably any loud noise would be). It will be interesting to see any data they can collect out of this on the benefit in practice.
- smegel 10y agoSounds more like white noise to me. What makes it pink??
- wingerlang 10y agoI don't know really know what this means tbh, but here's an explanation: http://www.acousticfields.com/white-noise-definition-vs-pink-noise/ http://www.acousticfields.com/white-noise-definition-vs-pink...
- jrockway 10y agoIt's white noise with a different power distribution; low frequencies are louder: http://i.stack.imgur.com/MMr0a.png http://i.stack.imgur.com/MMr0a.png
- eyuelt 10y agoRedshift
- leblancfg 10y agoThe sound is distinctly crisper on BigQuery, though. Of course, cables can make a difference but not always -- use CAT-8.2 if possible.
- timpattinson 10y agoBecause humans hear frequency in log scale, pink noise has more "even" distribution of amplitude to our ears. Pink noise -> 100-200hz has the same power as 10k-20k ie each octave has equal power AFAIK.
- wrigby 10y agoWhite noise is defined as having equal energy per frequency; that is, a 10hz wide slice of spectrum centered on 100hz will have as much energy in it as a 10hz wide slice of spectrum centered on 1khz. Pink noise has equal energy per octave; the slice of spectrum from 40hz-80hz has as much energy as the slice from 80hz-160hz and the slice from 1khz to 2khz. Pink noise can be thought of as white noise with a very low-q (3dB per-octave, specifically) low-pass filter applied.
- martin-adams 10y agoI worked with an audio engineer on real-time video encoding hardware and he said that in audio compression, you can throw away audio data immediately after a loud noise because the ear can't pick it up. This is probably an oversimplification, but sounds like a similar technique in this safety feature. I like it.
- chipperyman573 10y agoInteresting! Can you completely discard it (as in, complete silence immediately after) or just compress the immediate bits after a lot more than normal?
- pvdebbe 10y agoI'm guessing that the data couldn't completely be silenced because then any heavy dynamic compression at playback would bring out the optimization and break the sound.
- martin-adams 10y agoSadly I don't know the answer. I was just the GUI engineer fascinated by the cleverness of how to compress audio.
- kimburgess 10y agoThis is actually a big part of how MP3 compression works. Rather than using straight up data compression, it uses a psychoacoustic model to simplify different components of the signal that are affected by masking. There's a nice high-level (human readable) technical overview here if you'd like to learn more: http://arstechnica.com/features/2007/10/the-audiofile-understanding-mp3-compression/ http://arstechnica.com/features/2007/10/the-audiofile-unders...
- kimburgess 10y agoI should add, as another side note / rabbit hole to those new to the art of 'fucking with brains through audio' — masking is also frequently put to use in mixing, particularly EDM and more percussive genres. To help squeeze every last drop of perceived dynamic range out of a track you can use a technique known as sidechain compression (http://samplesfrommars.com/blogs/tips-tricks/18999227-how-to-use-sidechain-compression-to-make-kicks-cut-through-the-mix http://samplesfrommars.com/blogs/tips-tricks/18999227-how-to...) to dynamically compress other components of the mix in response to (usually) a kick drum.
- hiharryhere 10y agoForwarded this onto my dad who is an ENT specialist. He responded: "The Stapedius reflex has been use for artillery gunners for decades but the pink noise use is certainly novel."
- arprocter 10y agoI was going to ask if this would work at the gun range
- ComputerGuru 10y agoThis is a comment from Reddit on the same [0]; though I cannot vouch for its veracity, I found it interesting nonetheless: Former Benz master tech here. I've spent a good bit of time diving into the nitty gritty of these systems. It uses all of the vehicle sensors to determine crash logic. You want to fire the pretensioners before the airbags if at all possible. This locks the occupants in a much more secure and predictable psition. Accelerometers can determine if something like a rollover is in progress. Heavy braking + high speed + sudden activation of the parking sensors indicates a crash before physical contact happens. It can use the radar on distronic equipped cars to predict a crash. If the vehicle is in a slide, and a sudden yaw correction happens, this means a collision has occurred, even if the airbag sensors haven't been triggered. This is useful because the airbag sensors are only good at detecting force in one dimension. It's even possible for the vehicle to determine to fire the pretensioners but no airbags based on occupant size and weight (determined through seat/steering wheel position and capacitive mats in the seats) and impact vectors. It will even do things like full field the alternator up to 18+ volts to slam the windows shut super fast in the event of a rollover. The actual detection logic fills a 4" thick book. It's a big reason those cars are so damn expensive. Mercedes doesn't fuck around with safety. If I had to be in a wreck, it would be in an S class. Hands down. 0: http://www.reddit.com/r/todayilearned/comments/59qhaw/til_new_mercedesbenz_cars_will_play_a_short_blast/d9avtav http://www.reddit.com/r/todayilearned/comments/59qhaw/til_ne...
- LeonM 10y ago> If I had to be in a wreck, it would be in an S class. Hands down. To be honest, I'd rather be in a Tesla, since no amount of smart sensors can replace a crumple zone. The S class in particular has a big engine (usually a V8), which won't play nice during a front end collision.
- 3chelon 10y agoCrumple zones assume a nice, controlled, head-on crunch. Not so useful against getting whacked in the side by a truck. But then, probably not much is.
- deleted 10y ago[deleted]
- gururise 10y agoFascinating stuff. Kudos to Mercedes-Benz for pushing the envelope and making driving safer.
- cpeterso 10y agoI often listen to pink noise while I work to suppress room noise and mask tinnitus. Ironically, I find it is also good for relieving headaches! :) I have a CD with hour-long tracks of just white noise (sounds like static), pink noise (sounds like waves), and brown noise (sounds like airplane hum). http://whitenoisemeditation.bandcamp.com/ http://whitenoisemeditation.bandcamp.com/
- audeyisaacs 10y agoYou can also use SoX! `[audey@feather ~]$ play -c2 -n synth whitenoise lowpass 400 highpass 40`
- Stenzel 10y agoThe pink noise in the video has some strange dropouts and is compressed. If you want to listen to real pink noise I suggest this: http://stenzel.waldorfmusic.de/post/pink/ http://stenzel.waldorfmusic.de/post/pink/ Source Code: https://github.com/Stenzel/newshadeofpink https://github.com/Stenzel/newshadeofpink disclaimer: I made this.
- JHHuijnen 10y agoDear everyone, Mercedes is a good marketeer and with best intentions they included protection of hearing in their campaign. I wouldn't blame them for not knowing and after having spent lot's of money on this it could be dissapointing to hear that in fact, the acoustic reflex arc, otherwise known as the stapedius reflex does not protect hearing against loud sounds. It is simply a myth that even among many professionals is believed. The facts are that the ear's transparency for sounds is traditionally tested with only a single frequency, around 226 Hz, and around that frequency the sound levels get reduced by the acoustic reflex. Thus it seems as if the ear protects itself for loud sounds and the myth is born although it has only been measured at a single frequency. Technology to measure the same prinicples for a wider frequency range is currently only available for a selective group of researchers and for the industry developing medical instruments in this direction (for which I work). We know that above 1000 Hz the stapedius reflex is doing the opposite of protection. It will increase the sound levels. I could explain why the reflex is doing this, why did it evolve like this during the last many thousands of years. It is certainly easy to understand that a couple of hundred years ago (before industrialization) no protection for loud sounds was actually needed and thus hearing protection is not a logical candidate for explaining why we have such acoustic reflex... Though this is not the point. The point is that Mercedes' feature is not protecting your hearing during a collision impact. They made it with best intentions and for that they deserve a compliment and credits. A little more info about the acoustic reflex that I consider to be correct can be found here: https://youtu.be/3a3Eeuhkh-c?t=1164 https://youtu.be/3a3Eeuhkh-c?t=1164 Feel free to try to get in touch with me as well if you want to find out more about this topic. Cheers Jos