Guitar tuner that uses phone accelerometer • Hacker News Board

Re: Guitar tuner that uses phone accelerometer

#11

Post by jonathrg » Mon, May 11, 2026, 10:14 AM UTC

hgomersall wrote: post #9

jmusall wrote: post #4

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).

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.

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.

Re: Guitar tuner that uses phone accelerometer

#12

Post by ramenat2am » Mon, May 11, 2026, 10:48 AM UTC

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.

Re: Guitar tuner that uses phone accelerometer

#13

Post by embedding-shape » Mon, May 11, 2026, 10:53 AM UTC

ramenat2am wrote: post #12

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.

> 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.

Re: Guitar tuner that uses phone accelerometer

#14

Post by tiluha » Mon, May 11, 2026, 11:25 AM UTC

adm4 wrote: post #2

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

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

Re: Guitar tuner that uses phone accelerometer

#15

Post by ckocagil » Mon, May 11, 2026, 11:36 AM UTC

hgomersall wrote: post #9

jmusall wrote: post #4

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).

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.

aka a stroboscopic measurement,

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

Re: Guitar tuner that uses phone accelerometer

#16

Post by ErroneousBosh » Mon, May 11, 2026, 12:12 PM UTC

jonathrg wrote: post #11

hgomersall wrote: post #9

Earlier quoted context omitted.

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.

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.

If the accelerometer samples at 50Hz, how could there be an antialiasing filter?

What would that filter look like?

Re: Guitar tuner that uses phone accelerometer

#17

Post by KeplerBoy » Mon, May 11, 2026, 12:13 PM UTC

ckocagil wrote: post #15

hgomersall wrote: post #9

Earlier quoted context omitted.

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.

aka a stroboscopic measurement, but I don't think it will work well for this case.

It's just higher nyquist zones.

Re: Guitar tuner that uses phone accelerometer

#18

Post by nubinetwork » Mon, May 11, 2026, 12:33 PM UTC

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.

Re: Guitar tuner that uses phone accelerometer

#19

Post by colanderman » Mon, May 11, 2026, 12:36 PM UTC

ErroneousBosh wrote: post #16

jonathrg wrote: post #11

Earlier quoted context omitted.

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.

If the accelerometer samples at 50Hz, how could there be an antialiasing filter? What would that filter look like?

Anything physical which dampens higher frequency oscillations would act as an antialiasing filter.

Re: Guitar tuner that uses phone accelerometer

#20

Post by beezlebroxxxxxx » Mon, May 11, 2026, 12:39 PM UTC

nubinetwork wrote: post #18

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.

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.