Guitar tuner that uses phone accelerometer

https://tautme.github.io/phone-sensors/accel-tuner.html

by adm4 • 3 months ago

176 102 3 months ago

tautme.github.io

adm44• 3 months ago

guitar detuner that uses accelerometer instead of microphone, it doesn't really work, but amazing to see how sensitive they are.

tgv• 2 months ago

It also shows that it can leak all kinds of other information.

codethief• 2 months ago

…which is why both Android & iOS put high-frequency access to the accelerometer behind an additional permission AFAIR.

tiluha• 2 months ago

It really is crazy. Placing my phone on my chest lying down i can clearly see my heartbeat on the graph

adm44• 2 months ago

good idea https://tautme.github.io/phone-sensors/heartRate.html , try setting it on the ground and see how sensitive it is to foot steps.... or earthquake https://seismosense.com

virgil_disgr4ce2• 2 months ago

it detunes guitars?

pimlottc• 2 months ago

It tunes every string to D

jmusall• 2 months ago

Fun idea and also I didn't know that websites could get access to my accelerometer data. However for me the sample frequency is 50 Hz which is way too low to measure even the lowest string pitch (E2, about 82 Hz).

hgomersall• 2 months ago

If you know you have a single frequency close to an actual frequency of interest, you can use the fact you know you're in an aliased band to get a precise frequency estimate.

jonathrg• 2 months ago

Presumably there is an antialiasing low pass filter somewhere before JS gets to the data. I have a similar sample rate and it certainly didn't work at all for me.

ckocagil• 2 months ago

aka a stroboscopic measurement,

but I don't think it will work well for this case.

superxpro12• 2 months ago

I guess thats sort of like a weird PLL thing? But I'd imagine you'd have to have prior knowledge of which string you're tuning otherwise the analysis is going to alias against every harmonic.

peheje• 2 months ago

https://sinceyouarrived.world/taken

lightedman4• 2 months ago

"the lowest string pitch (E2, about 82 Hz)."

My 6-string Kiesel Kyber bass would like a word with you while it sounds 41Hz.

ta2112• 2 months ago

I guess the low B should be about 31Hz

aa-jv3• 2 months ago

Anyone got a handle on the algorithm required to do this? I've got a pocketable accelerometer-enabled device I'd like to try to implement this on..

simonklitj2• 2 months ago

Don't have a handle on it, unfortunately. But the algorithm is in here: https://github.com/tautme/phone-sensors/blob/main/guitar-tun.... Esp. lines 221–257 and 373–417.

aa-jv3• 2 months ago

Ah, that does look like something I can work with - thanks for the legwork, I will check it out and see if its worthwhile converting to C/C++ for my device ..

codedokode• 2 months ago

The code mentions "autocorrelation" method: this is a method where you multiply the signal with delayed version of itself: result = sum(x[i] * x[i - delay] for i in some range). You vary the "delay" and pick the value that maximizes the result. This is based on the idea, that the sequential periods of the signal should be similar to each other.

Not a very good method, prone to octave errors (showing pitch one octave lower than the correct one). Furthermore, the "delay" is an integer which limits the precision, so you need to use some form of interpolation. Also it doesn't allow to recognize multiple notes sounding together. Also, slow.

You can read the paper on the "YIN" pitch estimation algorithm which describes the method in details.

I think FFT-based methods are more reliable. I did little experimentation and when measuring a pure sine wave, the frequency can be determined with high precision (tenths-hundredths of a Herz). Not so good in presence of a noise or multiple instruments - I tried to use descending from the hill optimization to figure out the pitch of each harmonic, but it didn't work out.

JoheyDev888• 2 months ago

The neat bit is that it doesn't necessarily need to sample 82 Hz directly. If the sample rate is known and the target is one of a few guitar strings, the aliased peak can still be useful. The tricky part is probably rejecting the wrong alias once the vibration signal gets messy.

ramenat2am• 2 months ago

I mean yeah, that's cool as a fun project. And I've also heard about a project that used accelerometers as microphones for surveillance. And while it's doable, even the cheapest crappiest mic would do a much better job at recording sounds for whatever is your goal.

embedding-shape• 2 months ago

even the cheapest crappiest mic would do a much better job at recording sounds

And if you don't even have that, use a speaker/headphone as the microphone, probably also better results.

kelipso• 2 months ago

It’s about what apps can do with just default permissions, no? Not about what’s theoretically possible given full access to the phone.

nubinetwork• 2 months ago

This sounds neat, but I think I owned a tuner for about 6 weeks before I could do it by ear... EADGBe isn't that hard.

beezlebroxxxxxx• 2 months ago

If you have a good external reference point. But it's also pretty easy to have your tuning drift quite a bit away from E standard if you solely rely on the strings. Getting a standard tuning is not the same as getting the standard tuning you want, exactly. This is especially true if you play in standard tunings below E, like C or B, where strings can be looser than the norm.

chpatrick• 2 months ago

It's not hard if E is in tune already. :)

jameshart• 2 months ago

Pack it up folks, nubinetwork has exposed the scam that is the guitar tuner industry. You don’t need a guitar tuner if you have ears; all the guitar techs and musicians who use them have bought into a lie. And obviously since guitar tuners are a waste of time, a tech demo showing that you can use the accelerometer in a commodity handheld device to pick up minute vibrations with sufficient accuracy to detect guitar tuning from a web page is just feeding into the hands of Big Tuner.

Seriously, this is the very definition of a shallow dismissal.

markvdb• 2 months ago

Pro guitar teacher here with over twenty years of experience teaching the guitar, and close to fourty years of experience playing the guitar. I still struggle with properly tuning my instrument by ear. Nothing wrong with my ears. It's just not easy to do this right.

dsego2• 2 months ago

For me it's hard because of tempered tuning, so each string should be slightly out of tune for everything to sound good. If I tuned by ear, I could get two open strings to match, but all the fretted notes and chords wouldn't sound good. On my ukulele I even tune one string down on purpose to make the fretted note sound better. And then there is the inharmonicity of overtones, and some strings have more noticeable overtones that influence how the pitch is perceived.

Hamuko• 2 months ago

I can tell if my guitar's significantly out of tune, but no way I'm getting an accurate tune without a tuner.

recursive4• 2 months ago

So what do you do when the lead singer is engaging in some stage banter and you need to tune between songs? IEMs? With what reference pitch?

lightedman4• 2 months ago

A good chunk of us are in tune (pun intended) with our instruments to the point that we can simply feel the vibrations and know where we are with regards to tuning.

I haven't touched a tuner in about half a decade.

mrguyorama• 2 months ago

IEMs

Absolutely. In orchestral band back in my high school days, between songs I would ask my friend on the tuba to give me a note for reference so I could tune the timpani. If you are in a band you should be able to manage to take a one second note and hold that by humming or something and tune up. I can't even read real music (I was a "percussionist" ie incompetent except at rhythms) and even I could do that. Better trained musicians than I could expand from there to the other notes you need.

You just need a single reference pitch. You can literally just play a sine wave into your headphones for a second on stage, or have your audio engineering guy feed you one. Or you have one of those dirt cheap tuners that clips to the fretboard to get you started.

The lead singer is engaging in stage banter partially to give you the time and space to do this. If your ensemble includes a pianist or a synth, you just have them slap a note for a reference.

GuinansEyebrows• 2 months ago

i'm like this at home for sure, until i want to play along to something in tune.

i'm also the one at rehearsal literally throwing TU-3s at my bandmates who don't have tuners on their boards for some reason. you have to have a tuner if you play with others. no question.

kingkawn• 2 months ago

The very clear and succinct description on the landing page makes me miss the bizarre antisocial charming quirk that people who made things like this used to be stuck with for their copy rather than AI generated language. Our cacophony of experience is quieting.

Akuehne• 2 months ago

This has some very interesting privacy and security risks. If the tech can do more complex frequency analysis, then couldn't it essentially be used as a microphone for a device that doesn't need permission.

weard_beard• 2 months ago

Sounds like you've got a great idea for a proof of concept for DefCon next year...

DANmode2• 2 months ago

Probably worth reviewing prior art for inspiration:

0) https://www.usenix.org/conference/usenixsecurity14/technical...

1) https://infocondb.org/con/black-hat/black-hat-europe-2014/gy...

smallnix• 2 months ago

I thought this has been done to capture keystrokes of a keyboard next to the phone already

2011 https://www.researchgate.net/publication/221609349_spiPhone_...

pc86• 2 months ago

It's a pretty well-known exploit that the CIA is capable of turning a lot of electronics with speakers into microphones. I imagine there is an entire classified backlog of things they can turn into microphones without the target's knowledge.

righthand2• 2 months ago

The CIA…plug a set of regular headphones into a microphone jack, open a recording application and speak into the headphone speaker, you don’t need a 3 letter agency for that physics open secret.

MomsAVoxell• 2 months ago

The accelerometers that protect the average hard drive are easily subverted for this purpose.

ge963• 2 months ago

Tangent but the hidden no-electronics bug "The Thing / Great Seal Bug" really crazy

amelius• 2 months ago

I mean at this point I'm going to assume that any semiconductor device with more than a few pins has an embedded mems microphone.

_blk• 2 months ago

it's not (just) the CIA, it's (just) physics

jrflo• 2 months ago

I don't think that's realistic. If you're looking at the acceleration sound waves cause against a phone's accelerometer, that's likely far below the sensitivity of the sensor- phones are too massive relative to the force of sound waves from speaking. F=ma, so the acceleration you're looking at is the force of the soundwave (tiny) divided by the phone's mass (relatively large). The only reason this kind of works is because you're putting the phone on an object that's mechanically vibrating. I suppose it would work in certain situations like putting the phone on top of a large speaker, but you'd never get the resolution to decipher audio from sound waves alone for a phone sitting on a desk or in a pocket

jjk166• 2 months ago

I doubt the sampling rate is anywhere near what you would need to make out dialog in a sound recording. You might be able to tell who is speaking though if you had a voice profile.

nullc• 2 months ago

This is why grapheneos creates 'sensors' as a permission. On android all apps can spy on you this way.

Tade02• 2 months ago

My accelerometer apparently reads at 200Hz, but due to a lack of instrument at the ready I had to "pluck" the handle of the office fußball table.

When the right defender is near the center I'm reading ~24.74Hz, so slightly above G.

virgil_disgr4ce2• 2 months ago

heh, a subacoustic G#?

Tade02• 2 months ago

I think the tuner is off by an octave - it has a lot of harmonics and sounded like a G on a bass guitar.

tclancy2• 2 months ago

This was the direct inspiration for Total Football: to find harmony with the pitch.

AtNightWeCode• 2 months ago

Cool. It worked for E and A but it failed for string 1-4. I was surprised that it worked at all.

dehrmann• 2 months ago

The more reliable guitar tuners do something like this. You clip them on the neck, and they detect vibrations in the wood rather than from sound in the air.

foobarian• 2 months ago

Violin/other strings tuners tend to have this mode for orchestra uses with many people next to you also making sounds.

soperj2• 2 months ago

oddly, this is how I learned to tune my guitar. I'm pretty tone deaf, but can feel the difference between the reference string and the string I'm trying to tune through the guitar.

DANmode2• 2 months ago

This is fascinating.

Thanks for sharing.

donclark• 2 months ago

Can an accelerometer determine when a car is having issues? Can it do the same for a human user's body?

adm44• 2 months ago

i remember hearing Porsche was doing some machine learning with vibration analysis to find car trouble. https://www.porsche.digital/en

emil-lp• 2 months ago

Yes, predictive maintenance on motors and turbines using vibration is quite common.

Guitar tuner that uses phone accelerometer

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