Measuring the Speed of Sound with an Oscilloscope...and Hearing Test

[@LolanBadeauxMakes]

Get 2 identical microphones with long chords. use the same speaker. set both microphones about a meter away to start a baseline value so both are reading the same wave length (on 2 channels) at the same location. then you can slowly move the second microphone away any distance you like. another meter further away is fine

[@themonkeyminds7252]

hi

[@frankbuss]

You could have eliminated all offsets of the speaker and microphone by measuring two distances, and together with measuring the peak as you wrote in your video, I guess you could get pretty accurate measurements. Next speed of light :-) Regarding your hearing test: I don't know if it is KZbin or your recording setup, but I recorded the output of your video with Audacity (optical s/pdif output at 44.1 kHz from a Creative SB X-Fi and optical digital input to another USB sound card) and there is no signal (except the click at the beginning) for your test sequence above 15 kHz. I created a 17 kHz test sequence with Audacity and did the same test and it worked. Maybe add a note to your video so that people are not worried that they can't here above 15 kHz anymore.

[@TheRAZZITEAK]

I think your measurements might be more accurate than you think... The røde videomic that you've used hasn't got the actual microphone element at the end of the tube, it's actually recessed at the back of the tube. If you do the calculations with the 0,3ms error that you got (v*t=s) v is the textbook example of 340m/s, you'll get 0,1m (10cm) witch looks roughly like the length of that røde mic tube. So in fact, you've got very good numbers in this test :)

[@jayt3751]

mic element is at 1130mm

[@mjlorton]

TheRAZZITEAK Aaah...so not that bad then. Thanks for the post.

[@ppboyne]

I just did this experiment. I used the equation t_travel = distance/speedofsound + t_lag, where t_travel was the time for the sound to go from speaker to mic, distance was how far the mic was from the speaker, speedofsound is the speed of sound, and t_lag was the "lag time" in displaying the signal 2 from the microphone. I took 10 data points from 10 cm up to 100 cm. I graphed y = mx+b, where y was the travel time and x was the distance. I found y = 0.002820x + 0.000184 after graphing time in seconds and x in meters. My slope was one over the speed of sound. This yielded the speed of sound = 355 m/s. I am a physics teacher and am about to have my students try the same lab. Thank you very much for this inspiring video!

[@strayxray]

Take two measurements (e.g. at 0.5 meter and 1.5 meters), and use the difference between those measurements. That will correct for any processing delays introduced by your equipment.

[@samtzam3774]

Todd Geders Yes, this tecnique caled linearization, and the offset b is the addition delay. y=ax+b. Actually you need more that two points, but also with two you have a good approximation. web.williams.edu/Mathematics/sjmiller/public_html/BrownClasses/54/handouts/MethodLeastSquares.pdf

[@BASANTABHATTARAI]

thanks for the link as it was kind of intuitive article and goes whats wrong and how we fix it and goes very intuitive and step by step solution ..really loved it .

[@markbell9742]

The null that occurred as you moved the mic closer to the speaker was due to a standing wave (?) that was setup between the speaker and I guess a wall off camera to the right. If so, if you where to move the mic farther to the right you might detect other nulls. Lay some foam or carpet around/behind the mic and speaker to damp the reflections. Cheers, Mark *************************

[@friedmule5403]

Fun little measurement:-) I know that it was not scientific but here a few things that you could try. 1) To avoid sound bouncing af the walls and so on, use as high a frequency as possible. 2) Send as short a puls your system can work with. 3) Place the microphone and speaker as near as possible, to calculate the time it takes for your signal to go out the signal generator, through the wires, into the recorder and back into your scope. 4) Try again:-)

[@warywolfen]

The way I'd do it is this. I'd have two identical mike mikes placed a certain distance apart. I'd drive a speaker with a pulse. The first mike would turn on a gate, to allow a clock signal to pass. The second mike would turn it off. By counting the number of pulses that passed through, and knowing their frequency, the speed could be determined. By the way, I like the phase difference method you describe, it's quite clever.

[@TheBegoing]

I have discovered your channel several times on my curious queries of how to measure things and you have answered so many questions. Just wanted to says thanks you have improved my knowledge that I have used to apply to diagnostics of my solar experiments, and impress my friends... side note women still aren't impressed by me being a geek haha

[@paulrautenbach]

If you measure at more than one distance and draw the graph of the resulting travel times, you can discount the microphone processing delay as this will be a constant offset for all travel distances.

[@1951split]

I did the same experiment, but in a much less complicated and in a more wallet-friendly way. I just used two 27mm piezo buzzers and, without amplification, hooked them up to two probes . Then I put them apart by roughly 1,5m and clapped my hands making sure I was standing in line with the two piezo elements. Single shot trigger on channel one and "Bob was my uncle" like Dave would say... $ 3,- max (excl. scope) :)

[@ElectroMac74]

excellent job. maybe the diaphragm of the mic is little farther in the enclosure, that may explain the additional delay

[@jamisonw.327]

It's a very cool experiment and it's pretty awesome you just happen to have a 8 year old daughter to test the audible range on lol. Unfortunately what another person said about KZbin cutting off at 15khrz is true. Beyond this, some sound cards will also cut off somewhere between 15khrz and 20khrz. It's usually sudden though, so you'd be able to tell. So I would definitely recommend going to the link provided in the description, as that (at least for me) was able to show my peak at around 16.5khrz.

[@UDX-340]

This was a excellent video,I found a certain SW frequency to determine battery health during charge and discharge phase to my ears only[not possible so far in tests or theory],and went on a few year frenzy and always end up getting discouraged....This video got me interested again to see if i can match multiple frequencies to determine battery health with charge or discharge.

[@aliemad9455]

Thanks for your efforts❤

[@ppdan]

You should have made a differential measurement since this would eliminate any delay. For example : measure it at 10cm and then again at 110cm. Now use the time difference for calculating the speed of sound.

[@mariyamjoona679]

That frequency Hertz my ears.😂.but thank you so much for making this video❤️

[@akiosorah1916]

Gcse?

[@warywolfen]

Oh, gee! that "hearing test" turned out to be a damned good test for my somewhat crummy little speakers! They are little Harman Kardon powered speakers. At 13 KHz, they really started to put out. I didn't think they were that good, lacking tweeters, as it were.

[@DonSolaris]

The delay you were getting via Zoom recorder is a standard delay due to A/D converter in the unit. I think two piezos would make a better measurement - one to transmit other to receive. You can measure voltage straight off them. And one tip: to avoid that annoying tone all the time, simply use 20kHz signal. While ears don't hear it, mic will grab it perfectly.

[@redcatimaging]

Nice to see you experimenting and using one of the scopes. The microphone amp does make a delay, so a 2-point measurement or unamplified would have been better. You could use a little piezo (perhaps with an opamp) as mic too. And theres one tip I would like to give you for a long time from a photographic standpoint (as I work in portrait photography industry)...please set your camera a litte higher, it does look much much better Martin when you are not filming from below your chin (wideangle is also not that great, but I can understand that you want to show as much of the lab as you can..). Keep up your good work (actually I wish there were more often videos from you ;) ).

[@Gringo_In_Chile]

Nice video. It would be better to use balanced audio (+4 (3 conductors per channel (RTS))) equipment with XLR connector instead of unbalanced (-10 (2 conductors per channel)) mini plug connector. I guess you would need a matchbox impedance transformers on the I/O in your setup. Anyway my point is that unbalanced audio is susceptible to all kinds of interference like from LED lamps etc. Just my 2 cents worth.

[@jlfqam]

Thanks for the video. If you make a series of measurements at different distances and plot the values of time delay vs distance. A linear regression (trend) should give the true speed (RECIPROCAL 1/v) in the slope and the microphone response delay or offset in the intercept of the equation y=slope*x+intercept (delay=(1/v)*distance+offset).

[@ottokrauth7387]

Martin, Great video and experiment, truly enjoyed it.. I am going to try my own test and compare with your results. Cheers Otto

[@charlesbrewer6552]

HI Martin. Thanks for the video very interesting, it gets the mind going. My thoughts are that the distance measured may be out. Maybe from the coils in the speaker to the element inside the mike. I think you measured to the front of the mike housing. You may be closer to the value than you think. Great Work!

[@hardikchawla645]

+mjlorton how did you connect the speaker to the function generator and the oscilloscope and how did you connect microphone to the oscilloscope

[@donovanpl]

I think I've detected a flaw in the experiment. Correct me if I am wrong. The sound being generated is a series of single shot of sine waves. If we did not know the speed of sound as a reference to check for accuracy, how do you know that the mic signal to the right wasn't some multiple of the originating wave being received by the mic? ... If that makes sense.... A better way would have been a single burst of an event captured by the mic. Or am I incorrect?

[@tullgutten]

19:50 I think you have the speaker wired backwards and should measure from the first peak from source and the first significant peak on mic, in this case I think it would be the first negative peak. Edit: you should also do a "Calibration" test with them at no gap at all to find the delay time from wires and the processing in the microphone

[@tullgutten]

or even better, have 2 microphones and one sound source. Speaker---10cm---Mic,Mic Calibration test right right besides one another, then the distance test. Speaker---10cm---Mic-----------------------------------1Meter-----------------------------------Mic

[@algo_rhythm]

I have been trying to do this experiment using a DIY single channel Oscilloscope. I am doing a time delay measurement as well but cannot make the set up work. Any suggestions or alternative methods would be appreciated!

[@raguaviva]

you are getting stand waves, that is what at some points the mic goes flat

[@mauricioposada8270]

"Not Scientific." ??? Sir, that was certainly good science by a man of science. Great video. Thank you.

[@Raldenaldrin]

How do you connect the positive and negative terminal of the oscilloscope in the videomic?

[@JoeJ-8282]

I wish I had a good o-scope!... I've always wanted one ever since I was a kid tinkering with electronics, but I've never been able to get one because they are SO expensive! :(

[@TheBreadboardca]

Very cool demo Martin, nicely done. Ill take you up on your challenge and raise you something a little faster... :)

[@KX36]

The mrs and I can both hear up to 15kHz. Most likely though my laptop not being an expensive 20Hz-20kHz hifi has an audio bandwidth of say 100Hz-15kHz

[@haze42082]

Is there a way to test ribbon cables and fpc connectors?

[@vampifrog]

I too am a 15 kHz man.

[@prod.hxrford3896]

14:20, yeah, except nobody actually does that... There's no reason to hide a ringtone, there's literally no advantage when you can just put it on silent and feel it ring. Also a 16kHz tone as a ringtone would sound fucking awful. So again, nobody actually does that...

[@hang-sangitch]

Hi. How do you measure the frequency of sound?

[@waltercarrillo6065]

excellent

[@vgclipshd9198]

Can I have some of that kit mate gotta do a core practical and we're using stone age gear

[@cees1910]

I am 62 could hear to 18 khz

[@GoldSrc_]

Nice, I've seen this being done with video and counting frames :D. Also KZbin kills frequencies over 16-17KHz.

[@JoeJ-8282]

Lol, yeah; I would never trust *any* video on KZbin for a "hearing test", because of the high *and* low-end frequency cut-off points, but also because of the added distortion! I know his frequency tones are *MUCH* cleaner than on this video if heard in person in his workshop, etc., because I have a professional audio frequency generator myself, and the audio sine waves coming out of it are extremely clean and undistorted if listened to directly from it with headphones or when connected directly to my stereo system!

[@TKomoski]

Keep it up Dude

[@robertcalkjr.8325]

Interesting. Thanks Martin. I guess I've fired too many guns...

[@اتعلمبالمجانمعجمعة]

NICE

[@yaghiyahbrenner8902]

Is the power supply phase over?

[@mjlorton]

***** No, should have the next one out in about two weeks.

[@Theo-qz7wm]

nice noise

[@MrMaaalek]

Your measurements can not be accurate because the speaker has a relatively large mass (inertia). A better method is to two microphones (preferably identical) set at a distance of 1 m in a straight line with the sound source. The first microphone as a trigger, the second as a measure. Sound source does not need to be a speaker (generator) - just clap your hands. sound source --------- trigger mic ----------- 1m ----------- measure mic

[@NolanManteufel]

MrMaaalek ... exactly my thoughts too.

[@lovemyself252]

It's written on edexcel igcse physics book😑

[@icehengeUK]

would love to watch but the tone got way too annoying, perhaps try with ultrasonics and just annoy the dogs then

[@mjlorton]

icehengeUK No problem...I got annoyed editing this video!

[@z64fx79]

mjlorton Can KZbin account owner delete a post from a viewer if He/She don't like that comment ?

[@JGnLAU8OAWF6]

Tekken 10 Yeah.

[@z64fx79]

Антон Южаков Are you 100% sure ? I though only admin can remove it.

[@JGnLAU8OAWF6]

Tekken 10 Well. i am not 100% sure, but i think so.

[@TechnologyCatalyst]

You inspired me to give this a go! I used two electret microphones one meter apart, then used my clapper board to trigger the scope. I set two cursors and the time between them was EXACTLY what it should have been for the speed of sound in my lab. (I did the math for the temp, humidity, and pressure in my lab) 2.88 ms for 1 m. Brilliant! kzbin.info/www/bejne/npK5pKZ6gdZnfas

[@TechnologyCatalyst]

mjlorton oops, forgot to tag you in the comment so that you'll see it

[@airjammer0]

Im 20 and could only hear 13khz

[@Hvtesla]

+John Addison I'm 61 and also had 13khz, so goodness knows how low it will be for you in 40+ years time :-)

[@Gooberslot]

How old are you if you don't mind me asking?

[@mjlorton]

***** 44...45 in July.

[@Gooberslot]

mjlorton Then you're doing better than me. I'm younger than you and I can only hear to 15khz also.

[@terthue]

Teksten er bra

[@TKomoski]

Go

[@NoxMarcus]

Yeah, I'm not going to watch this, sorry. That sound is too annoying. (Tapping out at 8 min in.) If you apply a notch filter you can remove or at least reduce the tone to a reasonable level.

[@donbeckham]

Completely unwatchable.