Bass: The physical sensation of sound (2015) | Hacker News Reader

Bass: The physical sensation of sound (2015)

audioholics.com

98 pointspyinstallwoes61 comments

This is fun, I do haptics for a living and I would have never expected to have something to say here.

The way around the seat shaking problem is to use wideband vibrotactile actuators tuned to respond between 10 and 250 Hz on different part of the body. They can be embedded is seat or on a vest.

The mechanical energy transfer is local, can be tuned individually, and consumes much less energy.

There are also several successful products leveraging this principle like the Razer Hypersense line, feel belt, and others.

A recent company acquired by Meta, Lofelt, started their tech doing exactly this.

If you want to jump into the haptics rabbit hole, I animate a podcast [0] with some industry folks. Fascinating topics.

[0]: www.thehapticsclub.com

I make Techno. I would like to "feel" the sub in a way that doesn't require me to have a subwoofer. I know of things like Subpac but they don't sell them anymore. Do you know of anything else like this or if it is relatively easy to make one?

I'd check out the Woojer Strap/Vest [0] or maybe the ButtKicker [1] from the article if you're ok with being seated. I have stereo ButtKicker Concerts on my couch and they're awesome.

[0] https://www.woojer.com/

[1] https://thebuttkicker.com/

All these products are cool, the only issue is that they usually apply dsp to the sound and distort the output to enhance the haptics experience.

If he is looking to get the bass feeling of the music you want the pure input.

The Strap 3 is marketed for music listening, so I would imagine it would be workable? I've yet to try any of their stuff, though. The appeal seems to be around ease of use, and the targeted chest vibrations.

And the ButtKickers are purely mechanical, so no DSP. I would steer towards their Concert line as it's meant specifically for music, whereas the LFE has a stronger response from 20-30hz for home theater type applications.

I don’t know the strap 3, never tested.

For the buttkicker the real issue is the chair itself. It filters a ton of stuff and rattles.

A good experience are the Dbox chairs, the problem is that they cost 5 k.

Relevant club podcast with the CTO https://open.spotify.com/episode/6ERkgfJxm7QCZlp1p5eIGD?si=E...

You are right about dsp. Measurements (in russian) [0] https://www.dastereo.ru/t/subpac-m2-technical-review-dr-wehr...

Thanks!

I wrote few of these algorithms myself for some other products.

There is always a trade off between fidelity and immersive feeling because the basses were not meant to be used with such product in mind.

With my company, Interhaptics, we built a full stack pipeline only for haptics. Our tech is at the basis of the MPEG haptics encoding standard coming out shortly.

We have been recently acquired by Razer, look out for news of you are interested to build for touch natively

Quite easy to build. The problem is to get ahold of the parts.

Get a well know console controller, take out the two actuators and mount them in any other form factors you like.

You can drive them with an audio pipeline, they are effectively a 4 ohm speaker. Attach them to a sound card and you can have your stereo haptics subwoofers.

You have to filter out aggressively the resonance frequency of the actuator to get a flattish response. Not that subpac or the other folks do so

How many watts can those handle? I would imagine wanting something more powerful.

No idea, worst case scenario the stator comes out and you find your limit :)

The key is to mount them properly on the body to maximize mechanical coupling. You don’t need a lot of watts if the losses are almost zero.

If you want more, build an array of actuators and spread them out.

More immersive feeling compared to a stronger one.

I love bass. I have build a very large, "dub" soundsystem, which uses a 6,000 amplifier, 18" speakers and folded-horn cabinets which way literally half of a ton. It can literally shake the paint off of walls.

I also have tinnitus so bad that it's very disruptive to my life (which I had before I discovered the joy of big bass). One thing that I've discovered is that playing large amounts of tactile bass will make the tinnitus go away completely for a few days after playing, with the benefit lasting to some extent for a few weeks after. I've researched it and talked to some specialists who suggest there is a physiological basis for this effect, but that has not been properly explored.

I once attended a Bassnectar concert and he did live up to his name by giving the most distinctive bass performance I’ve ever experienced. As the show started he launched into heavy bass and the girl next to me immediately started crying and I found it difficult to control breathing. My throat and chest were so rattled it was difficult to effectively move air in and out.

Sounds great!

But seriously, I know exactly the feeling you're talking about. My wife and I went to a Darkside concert while she was about 6 months pregnant. The baby didn't move for a few days afterwards and we went to the doctor about it (who laughed, and said that they weren't in any danger).

Oh my god that must have been absolutely terrifying. Glad everything was okay. Can’t imagine the interim.

Longest few days of your life, I bet.

I ran in some heavy drum and bass circles willingly for years and one guy had a 1,000 watt 18” pa speaker in his 15x15’ rehearsal studio and it could be weaponized.

One time he played at San Jose State University while I was living in the brick dorms next door and I distinctly remember feeling the bass even from outside that show.

> at sound pressure levels above 166 dB, and at 171 to 173

That's pretty loud. At takeoff, the outside of turbofan aircraft engines are around 140dB. 130dB is where pain begins. Hardly anyone can hear 1Hz, but a few are cursed with subsonic hearing.

“Pretty loud” is an understatement because decibel is a logarithmic scale - every 6dB increase is an apparent doubling of loudness.

Also, no-one can hear 1hz - for us it’s a rhythm, not a tone. A grandfather clock ticks at roughly that rate, as a matter of fact (well, twice that rate if you count both the “tick” and the “tock”.

> Also, no-one can hear 1hz

True, except for those cursed with subsonic hearing that can hear frequencies below 8Hz down to sub Hz frequencies, and which is painful for them even at low sound pressures and from great distances, bizarre because these waves can be over 34,000x the diameter of the human ear drum.

Like who? I’ve never heard of this and am struggling to find any supporting material for your claims. Are you able to provide any?

The human range of hearing is only generally stated at between 20-20k Hz. Do you really believe that is a hard limit? Is it really so difficult to believe there are outliers? It is far more common to find individuals with supersonic hearing that can hear sounds above 20kHz, called ultrasonics, some that can even hear frequencies as high as 28kHz and higher. But even most people can hear sounds as low as 12Hz under ideal laboratory conditions. But frequencies much lower can be heard by a minority of individuals.[1][2] I have no trouble whatsoever hearing this[3] or this[4], though it... hurts. Diesel school busses are the bane of my existence, putting out frequencies between 5-8Hz that I can hear passing from 10 miles away from inside my house. If they're within half a mile, it kills me. There's no escape from it, plugging ears does nothing. You'll never, never ever see a black hole or dark matter, but I bet you have no trouble believing in them. But you're skeptical of subsonic hearing because Google sucks. Take my word for it, and be skeptical of Google instead.

[1] https://docs.wind-watch.org/OudM_journalGeluid_2013_03_EN.pd...

[2] https://pubmed.ncbi.nlm.nih.gov/15273023/

[3] https://www.youtube.com/watch?v=kEPswjA5-m0&t=0m4s

[4] https://www.youtube.com/watch?v=XV11rd-sJdg&t=0m4s

Hate to break it to you but everyone can hear those videos, they're not what they say they are. I downloaded the audio of the one that claims to be 1Hz and analysed it - most of the energy is between 40 and 60Hz, with some as high as 100Hz. I've uploaded a screenshot so you can see for yourself: https://i.imgur.com/GSpa8ZJ.png

The thing is, I didn't have to listen to the video to know it's BS, because I know there's no consumer audio equipment (speakers _or_ headphones) that will reproduce tones lower than 20Hz. As a matter of fact you'd be hard-pressed to find a subwoofer that will even do 25Hz. Go ahead, prove me wrong.

Note that I'm not trying to disprove or diminish your claims of what you personally experience. But I'm also not going to "take your word for it". I find it very hard to imagine what 1Hz "sounds" like, and so far nothing you've provided makes that gap any easier to bridge.

3 dB difference is a doubling/halving of amplitude. Not sure if that's what you meant with apparent loudness?

Energy of a wave is proportional to the square of amplitude, so I guess they took the square of the doubled amplitude in dB.

I mean how loud it sounds, the subjective “volume”. It’s not exact, but it’s a useful rule of thumb.

.. There was this French bloke at the turn of the 20th century who built a giant whistle that produced sub-bass frequencies of around 7.1 or 7.2 Hz. The first time that he got it to work, he liquidized himself. It just turned his insides to mush—poor bugger.

https://djtechtools.com/2014/04/10/funktion-ones-tony-andrew...

Someone knows more about it ?

Maybe Vladimir Gavreau? https://en.wikipedia.org/wiki/Vladimir_Gavreau

EDIT: who may or may not be the same as this "Professor Gavraud": https://www.dickbowdler.co.uk/content/publications/A_Short_H...

Those are incredibly interesting reads, thank you!

Yeah, this is good stuff. The device could kill a person at 5 miles away, but was just as dangerous to its operators as to its enemy. It could deliver tens of thousands of watts. Wow.

Perfect doomsday MAD device for something important but automated

So is that the official frequency of the brown note?

From looking at the patents I think it's less about a specific frequency and more about a power level. Infrasonics are defined as less than 20hz and higher than geologic vibrations like once ever hundred seconds or so. If I'd guess it's somewhere between .5 and 10 hz, but again it's not about playing something of that frequency, it's about delivering tens of thousands of watts to the air which just happens to be at that frequency

"who built a giant whistle that produced sub-bass frequencies of around 7.1 or 7.2 Hz. The first time that he got it to work, he liquidized himself"

specifically talking about frequencies liquefying someone. the quoted comment mentioned nothing about power levels.

the TFA is talking about power levels. that's a different conversation than the one you replied

That's my point, it's not the frequency that liquifys someone.

You could easily play a 7.1 hz sound on a good thx sub or concert sound system. Simply playing that tone would not liquefy someone.

At the same time, one could play a 6 hz or a 7.3 hz tone at the same power level as this guy did, and it would liquefy someone.

The frequency is the result of a bunch of other variables that are the true drivers of the phenomenon. Power level, physical properties of air and the limits to the power you can couple to it before cavitation and negative pressure regions occurs, resonance, and the geometry of your device. Put that all together, get it ringing, constructively interfering, and it will be at a certain frequency. It's the result of the equation, not the input.

More accurate to call it a “red note” I think

Playing standup bass, electric bass, and drums are unique musical experiences. You feel them in your gut. It’s therapy right along with music. When you’re in the pocket no one doubts who’s leading the band.

Our drummer hits hard. I don’t complain much, as I then can turn up the volume on my bass amp. You really feel the notes in your body. (Just don’t forget the hearing protection.)

One of my ears has significant hearing loss, and in the same time it's still very good at bone conduction of low frequencies tones. I can literally feel that neighbor from two floors above is playing basses, even though my spause won't notice this. There are times this forces me to go out since I cannot 'opt out' from sensing this. So one thing I'd like to say to audiophiles, please be aware that something beautiful to you might be causing lots of distress to people around you..

170 dB sounds massive, but when you convert to force/area, we're only talking about an extra 0.06 atmospheres of pressure[0]

[0]:https://www.translatorscafe.com/unit-converter/en-US/sound-p...

170 dB is super high, like a shotgun blast or a jet engine close by, or a hurricane.

This video goes into detail on dB ratings. It makes the point that these truck air horns that are labeled 300db on Amazon are actually many thousands of times more powerful than the Krakatoa blast, and would actually expde our planet. Spoiler, the air horn aren't actually 300 dB, they're more like 100-115. https://youtu.be/zAe9qvC49qY

An atmosphere doesn't sound like a lot, but it's actually a very large amount.

0.06 atmospheres of pressure, coming from one side, is half a ton of pressure on your body.

If the dB is high enough but the frequency is low enough, the "sound" is actually just a light breeze.

The minimum wind speed to reach hurricane status has a pressure level of 130kg/m^2.

That's 156dB.

170dB as a breeze is up around 160mph.

Sure. The sustained wind of a hurricane could be thought of as a 0 Hz 156 dB sound wave. A more ordinary passing breeze, the sort that we consciously recognize as a breeze rather than as a sound, lasts for around 1-10 seconds. So we could just as well describe an ordinary breeze as noise in the .1-1 Hz part of the spectrum somewhere above 100 dB of loudness (guessing).

Alternatively, sound is just a breeze too fast for direct conscious perception.

Very fascinating. I got interested in trying to understand the Science of Sound/Acoustical Engineering after reading the reviews of various Earphones/IEMs/etc. and of course "Hi-Res" audio equipment. A lot of it made no scientific sense and seemed to be completely subjective not withstanding their astronomical prices. The field seems to be plagued by gallons of "Snake-Oil".

Can somebody suggest some good books/sites on the following?

1) Study of "Signals and Systems" but using Sound Waves as examples.

2) The effect of Sound on Humans (and on living tissue in general).

For #1 there are a couple great youtube channels that cover a lot of the technical background on drivers and control systems (amplifiers) as well how to objectively compare and test audio setups. 1 - PS audio https://youtube.com/c/PSAudiochannel and 2 - Tech Ingredients https://youtube.com/c/TechIngredients

In this tech Ingredients video they go over some really well performing but very simple and low cost to make speaker and amp set, as well as a test setup to do objective comparison tests on different designs. https://youtu.be/GslJ8Hf4WwE

For #2 I've actually done quite a bit of work with sound and the body, in designing medical devices. It's interesting, sound travels very well through the body, why bone conduction headphones and ultrasound work so well. Most of the good info on sound and it's interaction with the body I've found to be in clinical and scientific papers.

I hope something here helps!

Thank you and appreciate the pointers.

For #2 can you suggest some beginner's textbook?

Gladly

This book is a bit broad, but I think it's the best place to start I know of:

https://link.springer.com/book/10.1007/978-3-319-23932-3

"The physics of the human body"

Thank you; The book looks quite encyclopedic in its coverage!

Gimme More :-)

For #1 I can highly recommend this interactive article by Bartosz Ciechanowski: https://ciechanow.ski/sound/. It might lack the depth you want in intermediate or advanced topics, but in my opinion it is the most efficient and effective beginner education material out there.

Nice site; the interaction aspect is particularly good.

Thanks for the link!

I also found this "University of Southampton" site on Sound really helpful : https://blog.soton.ac.uk/soundwaves/

It's a very broad topic you need to be more specific. Ultrasound can heat up tissues that's the reason why there's a time limit when doing ultrasound on babies and the machines beeps nonstop when the time is up.

I thought my questions were specific?

1) This is a standard "Signals and Systems" course for Analog/DSP engineering but where i would like to see practical hands-on labs using Sound Vibrations/Waves.

2) This consists of two major parts; One is the perception of Sound through the auditory pathway (including bone conducting) and the other is via the whole body (via what the article calls mechanoreceptors/thermoreceptors). How does it affect the Brain/Nervous System itself?

I’ve wondered about actually trying to set up a festival field or something with buried subwoofer type frequency generators so you could literally be shaking the ground in time with Skrillex

No need to put them inside the ground. A line array of 21"s sitting on top of the ground will do all the ground shaking you could ask for, especially in an indoor venue.

Excerpt from an article on sound waves / pressure and the sensations and effects related to various dB levels at cycle times.

Interesting video on bass I've posted month ago: philosophy of bass: https://youtube.com/watch?v=1xPO2Q2QHXk

Makes you wonder if 17-18hz is used for torture and "riot control"

Usually it's higher frequencies so it's directed.

See: "LRADs and Sound Cannons Are NOT Safe. Here's How To Minimize Their Effects. " https://www.youtube.com/watch?v=3sqIvak-4Ek

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