Beat frequency | Physics | Khan Academy

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In this video David explains what beat frequency means, howto find it, and solves a sample problem involving beat frequency. Created by David SantoPietro.
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[@juewang8073]

When I was a kid practicing clarinet, I always heard my teacher saying, "if you hear the wobble when you and I are playing the same note, then you'd probably out of tune. " 10 years later I can explain this in acoustic physics. Thank you Khan academy!

[@VeritasEtAequitas]

Yeah, but that also could just be embouchure on a woodwind or fingering pressure on a stringed instrument "bending" the tone too.

[@nicholasz2510]

@@VeritasEtAequitas OP didn't specify that it was specifically the instrument being out of tune, so incorrect embouchure/pressure also counts as "out of tune".

[@ElectroRestore]

It could also be the teacher is off and you are correct. Or you both could be off frequency in varying amounts ad divers directions. Tell the teacher, your right and she is wrong and it is a case of observer reality. :)

[@namankarn1504]

it's the best explanation i've ever come through..

[@saltypakoda5333]

When he said 'WaouUou', I felt that.

[@kliusd]

woah woah woah woah woah...woah woah...woooooooah thank you for your explanation

[@zpawn1]

When i was a kid, i used to get this same effect by screaming at each others face with my cousin. I didn't know the name of this phenomena until now, thanks!

[@GIobeCentral]

I appreciate your explanation of the word phenomena. Cheers!

[@noxusfumes3628]

@@GIobeCentral everything is a _phenomena_ these days lol 😂😂

[@noxusfumes3628]

Most teachers simply go into the math but your lecture was able to give me a 'feel' of what beats actually is. Thank you! 👍

[@cola5323]

Exactly, it makes such a big difference to be able to really picture the phenomenon happening rather than just having a bunch of formula to memorize

[@noxusfumes3628]

​@@cola5323 Agreed 💯 ... Btw your comment actually brought me back to this 3 year old comment of mine from the time when I was actually preparing for my medical entrance exams (they also ask physics in it) Feels good to just look back and see how far I've come (cracked the exam, into med school now)

[@cola5323]

@@noxusfumes3628 happy to hear that you’re doing great! :> keep crushin ‘em!

[@ghostnotbedsheet]

"feel"? Bro did you study physics from MR sir?

[@cola5323]

@@ghostnotbedsheet I think they meant like they’re able to understand beats on a more intuitive level after watching the video

[@axeledongo7846]

that Dr.Dre joke though

[@laze_amvs424]

I just heard it now and I'm dead XD

[@johnhebert7445]

I think he needs to edit a section in where he says “now I’m going to play both frequencies at the same time. You will definitely be able to hear the difference.” and play Dr. Dre. 😂

[@Saharah2050]

This is a really terrific explanation that I have ever heard. Thanks!

[@lakshmishajahan8391]

Now I finally understand it! Thank you!

[@VeritasEtAequitas]

Aaaand that, folks, is exactly how you tune an instrument, guitar or woodwind.
Sal is ok, but this guy is SO MUCH BETTER! Thank you! Please do more of Khan's videos.

[@sanar77]

i was really searching for this video

[@aryan___2k5]

Wonderously Explained! Thanks!

[@monchina5626]

Sir ur voice is wonderful.

[@lambda4931]

Very clear! Thank you

[@NiharikaAChirayil]

Thanks for the video! I had doubts on this topic.

[@tamalesux]

I’ve taken note of parts in songs that have a ‘beat frequency’ bass note because it sounds sick. I didn’t know the term for it but I had realized what the sound was when I had played around in FL studio and played 2 different frequency 808s at the same time. You learn something new every day. (One example is look at me now by Brennan savage. Will be easier to tell with a system or just a sub in general)

[@sunilgoyal2957]

Excellent. Thanks a lot

[@kayo6955]

thank you so much, that was an amazing explanation. Thank you

[@manoharaswamyjm1675]

No words to talk about explanation
I'm impressed 👏🏻💯

[@samstephens891]

Very helpful explanation, thank you!

[@dcqec111]

I love his voice.

[@kimsmith6384]

mee too

[@pournimathakare2279]

simply awesome!!

[@GIobeCentral]

I like this video, and your analogy using musical instruments.

[@akashhera]

This video helped me to get a clear idea on beat frequency other than some set of equations!

[@khatonredwood6570]

U explain so well...hats off

[@faithralane214]

Thanks very helpful .

[@ClumpypooCP]

Really a great explanation. Awesome stuff. Thanks

[@orangeinfotainment620]

Thank you!

[@zSatherz]

Such a good video. It is entertaining and extremely informative. AWESOME.

[@dailymech4850]

Simply,great.

[@geoffphillips8183]

Excellent explanation! Thanks

[@NToB36]

youre amazing!

[@MuhammadRaza-yd6sg]

Keep up the good work guys 💙💙💙

[@migeto4721]

Wooow I still enjoy your lesson ever I watch

[@sibgha9966]

Thank you so much

[@SherlockHolmes-lc7jo]

Well explained...

[@divyahinduja3424]

thank you so much 🙌🙏🙏

[@candypaii]

Thanks!

[@dnlgrg]

Thank you

[@Spear8]

You explained really well man . Thank you everymuch🙂

[@dr.nupurbanerjee9547]

Ty

[@linatewala9471]

thanks!

[@syedashabanazaidi6262]

Sir keep up the good work god bless u😇

[@AnkitaTiwari_no1]

Best explanation of beats thank you so much sir

[@rnumashankar2857]

Thanks sir

[@sangitapawar6490]

Best explanation ever...

[@Min-sj8xt]

THANK YOU you just saved my physic test score

[@yuktamasta7130]

Nice explaination

[@aadarshsbhat7148]

thanks

[@av_yukt]

u r too good sir....

[@ifesvlog]

Thanks

[@maxxxlearner7066]

best explanation of beats

[@R.Bharathkumar2003]

Thank you you are considering south people too and said this in English I will be thankful to you for your concern

[@ryanbortz7694]

Great video. One clarification: when the flute and clarinet are both playing the ‘a’ in tune, they will be playing in unison, not harmony.

[@johnmifsud6814]

Fantastic explanation - not just babble from a physics dude. The output of beats is confusing as one is expecting something like a Sine wave compared to an interfence pattern. This makes it more difficult to comprehend the resulting frequency. This video explained it beautifully - very well done...

[@musictheorytree]

I love how the quality of beats is related to the quality of intervals.

[@sushilskolia]

Challenging the teaching of expensive teachers snd winning by an edge….. super awesome

[@NJ-co6qs]

amazing explanation 😊😊😺😺👍👌

[@GauravRaghav]

awesome video

[@Garmashua]

Who knows any app/program that let me see graphs and play with sound? Thanks

[@point-og3yc]

Nice explanation

[@gabor6259]

This video made me go wowowow.

[@forgamerz1]

awsome

[@roseb2105]

by wobolly do you mean that the waves from the 2 different sources are not aligned ( neither constructive nor destructive)

[@magnuswootton7368]

do the lesson in wave length.

[@hritikgogoi3577]

🤗 soooo nice..

[@sharonjuniorchess]

Not only is this used by musicians to tune their instruments but it can be applied to make continuous wave (morse) radiotelegraphy signals audible.

[@drshr2009]

If the two waves with the same wavelength are in between constructive and destructive interference, won't it be constructive at some points and destructive at others?
Also, I just realized that you can think about beat frequency like two runners around a circular track - the difference in frequencies is how many more cycles the faster person is going to do in a second! If you want to know the first time the runner will lap the second runner or the first time these runners meet again if they start from the same place, you can do f1 (faster frequency) * t = f2 * t + 1 (for one more cycle). This will give you 1/(f1-f2) seconds.
If you believe me that this time stays constant, in 1 second, you have 1/(1/(f1-f2)) constructive interferences or a beat frequency of f1-f2!

[@cola5323]

A beautiful demonstration of how music and science are intertwined! I know that music is essentially science but there’s this idea that music is in complete contrast with cold hard science and that’s just not true!

[@BernardoHenriques4]

Can someone clarify me something? I was doing some research on beat and came across a book that stated the frequency you HEAR is actually double the ACTUAL frequency of the beat.
ie: if you hear a beat sound of 20 wobbles per second the difference between the two frequencies playing is actually only 10hz - and not 20Hz. The reasoning is that for every wavelength on the new wave formed you'll hear 2 beats.
The way David explained made it seem that the frequency you hear is the actual beat frequency. Can someone clarify me on this?

[@srs.r6354]

Nicer👍👌💐

[@MinuteMayne]

dre jokes hell yeah

[@rogerscottcathey]

what would the harmonic be? 883 bps?

[@johndoe-bq1xt]

Sir, I have a question. If i have f1 and f2 and I get fb1=abs(f1-f2). If I added f3. Would I get fb2=abs(fb1-f3)? And could I do this for more frequencies?

[@Mohamed-jv6nv]

Thanks. Amazing videos. it'd be more than perfect if the visuals were better IUKWIM ;)

[@gregorykarimian3813]

Beats By David

[@daraquesca1886]

4:55

[@daraquesca1886]

2:30

[@tharindunawoda]

❤❤❤❤

[@daraquesca1886]

9:00

[@aabidsofi19]

I wan Dr.dre to do this woo woble

[@abhishekpandey-hf7on]

If beat frequency be in decimal, suppose 8.13 then we will hear 8 wobbles per second, ??

[@amannautiyal9992]

Dr. Dre!!! 😂

[@tanjimirtiza2366]

xDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD I LAUGHED SO HARD HEARING THAT JOKE

[@cliveaw1206]

I don't why but this guy reminds me of the little bits guy from rick and morty

[@coloradowilderness3139]

Wrong at 4:17, It will be constructive in the opposite direction .

[@spectrum792]

You just played 440 Hz & then you're saying the frequency is 20Hz. How come?

[@daraquesca1886]

230

[@daraquesca1886]

hello

[@akshaykarthick7822]

thank goodness ! I thought dr.dre's rival would come out of this ! ( anyway, good joke)

[@mdbarjahan6695]

It's look like modulated wave.....Isn't i???

[@russelbymahlawule496]

Those people who hit the dislike button are probably going to dropout

[@XWRL00]

5:24 and I stared freestyling

[@pawanramnani8300]

School teacher send this btw school is full waste for jee prep

[@sanar77]

are you real khan means (pathan) plz answer.

[@Upgradezz]

Is khan Muslim ¿

[@godhelpme8977]

HOT WATER GIRL

[@praiseekakitie1056]

Thanks!

[@sampadaghalsasi1565]

thanks!

[@SangitaKumari-og9gy]

Thank you