Interference Demo: Speakers

This is a demonstration of the interference pattern created by two speakers playing the same 2000 Hz tone. It is carried out by moving a microphone through the sound field and noting that the sound is louder in some spots (those with constructive interference) than others.
This demonstration was created at Utah State University by Professor Boyd F. Edwards, assisted by James Coburn (demonstration specialist), David Evans (videography), and Rebecca Whitney (closed captions), with support from Jan Sojka, Physics Department Head, and Robert Wagner, Executive Vice Provost and Dean of Academic and Instructional Services.

[@mszuri24]

Actually seeing a demo makes the book word problems make more sense. Appreciate it.

[@physicsdemos]

Thanks!

[@physicsdemos]

Thanks!

[@matetotally]

@yeahSOwhat pretty simple, the demo makes sense of whats confusing when read in a book.

[@AkashDarwinBowse]

@yeahSOwhat "Does that first sentence really make *_a sense_* " lol if you're tryna correct others make sure you're doing it right first xD

[@godhelpme8977]

Hi

[@parjitkhakh6970]

Seeing and understanding how the waves cancel due to superposition from the book is one thing but actually hearing , or the lack thereof, the sound cancelling is incredible.

[@simonmoore5978]

How amazing, a whole world of physics invisible to the naked eye but able to be perceived by our other senses. Thank you so much for the demonstration!

[@samk35]

That's the beauty of nature

[@ajeyhegde7147]

I had thought that such a thing wouldn't happen in reality but after viewing this demo, got convinced with things. Thanks a lot!

[@gayatri9627]

My favourite channel for physics, it makes the content written in the book living and real... Amazing!!!!!

[@kevinpolpitiya3200]

Thanks for the demo. Due to the lockdown we are unable to perform these experiments individually. Hence we must rely on videos on KZbin. It was difficult finding a decent video to represent this topic. This was great!!! Thankyou!!!

[@creatureofvenice]

Thank you so much! This is the best video I could find for this!

[@BrentMurrell]

nice soothing tone you chose there lol - thanks for the demo, really appreciate you

[@r.a.6459]

This is the sound variant of the double slit experiment. Awesome.

[@sam-hk4ru]

Wow that's amazing to understand an gorgeous experiment

[@markpaul7746]

Very interesting. Thanks for uploading this!

[@manjumeo8818]

My physics teacher ask us to watch it , really amazing explanation 👍

[@physics20246]

exordinary work and effort, thanks sir

[@antonybrun3845]

That is actually really cool, thank you!

[@hetdave8679]

Awesome demonstration 👍👍

[@prateek3167]

loved it soo much cant tell you , i was struggling from a long time to understand interference because its boring as hell.but you proved today that it could have been so interesting.

[@ramennight]

Thankyou! I've understood what interference has done to waves, but not what that means to me in the practical sense.

[@djijspeakerguy4628]

I’m pretty sure this interference is called comb filtering. If you move around while playing pink noise, you’ll hear certain frequencies start to pop out, and a sweeping noise as you move. Sitting in the exact center in a concert, for this reason, will usually sound the best by far. It is worth noting it has to be the exact center.

[@kristyevans5143]

saw an explanation video 1st.. didn't get it..searched for some other explanation video but got your experiment video and man I didn't know it was so easy to understand

[@21.akashhiremath12]

Thank you sir For explaining in the best way

[@kaik3122]

fax yo

[@sikretp]

thank you for sharing the insightful knowledge. 👏👍✨

[@lucyaddictfrog]

Thanks for the video:) rlly helpful!

[@occultbass]

Life is crazy! The fact stuff like this exists is crazy! You are very intelligent!

[@kaik3122]

fax yo

[@evodem]

Also a great content for music producers right here! Thank you i will try this out at home! 🎉😊

[@mariestewart998]

Amazing.

[@pubs8837]

Love Mr. George Kafentzis, best physics teacher EVER. Hope I pass your exam tomorrow :P

[@pubs8837]

Passed with 6 :)

[@SachiN-Vishwakarm]

thanku sir.....for this experiment!

[@pkart8451]

Finally I find such video

[@nehemiahshird2154]

THATS MY SCHOOL!!! UTAH STATE UNIVERSITY!! GO AGGIESS

[@TerrenciaVlogs]

Nice video, I was reading about this experiment in my text book but found it hard to visualize what they were saying, excellent video!

[@Zahraa-hg4vq]

Thank you so much

[@dhairya-varshney]

A good presentation. Thanks to the video makers. By the way how did you manage to keep a constant phase difference between those speakers.

[@CheapHood]

Helped a lot

[@physics20246]

Sir, though I am very far from you, we are very close to your heart, your teaching inspiring me in so many ways

[@Ayana781]

Thank you

[@lalitmohanverma3466]

Very good explanation provided by sir.

[@guqinbeats]

Thanks 👏

[@user-wr1gh8fv6p]

Thanks

[@vaishnav4035]

Thanxs

[@jeppekristoffersen9834]

very good video love u:)

[@tennicktenstyl]

That's why headphones are superior

[@dingdong5231]

If there is equal distance from two speakers to microphone then ... constructive interference is producedand if not then, destructive?? Plz answer

[@TeacherNorainikhal]

WHAT IS THE DEVICE USED TO DETECT SOUND?

[@gregorypoe7289]

I wish there were shorter versions of these demos. Whenever I play them, I lose the kids' attention before the actual demonstration begins.

[@mirsaba4081]

My physics teacher told me to watch it ❤️

[@ah.l]

After this demo I am expecting to see object tracking dsp in speakers sometime in future.

[@kemmuannisa8451]

so its better use 1 speaker ?.....

[@tanavposwal]

Amazing looking for same

[@julian3471]

dr. boyd = bae

[@lieutenantshibby]

Is this what navani and eshonai discovered in stormlight archive?

[@milikumari5474]

If destructive interference cancels out ( nearly) and the locations have minimum energy .. So is it possible that we can cancel the shockwaves of earthquakes by superposing man made earthquake waves and reduce damage to property?? theoretical possibility?

[@divyamankotia6035]

destructive kam hoga but constructive will be more than amplitude of earth quake.... Maybe we'll be able to cure this in near future

[@Mikeological]

I may be wrong here because I’m not in any way an expert so someone correct me if I am. I feel like it wouldn’t be a great solution because earthquakes (and the man made one in question) propagate in a spherical pattern. Making an anti-earthquake would create areas where it cancels out, but it would also create areas where it is amplified as mentioned. I guess it could be possible to find the exact epicenter and start producing an exact opposite waveform from the same point (the same way active noise cancelling headphones work) but that would be interesting to find out how to create them to be identical and opposite, find out how to center it exactly, and find out how to do this all while standing in the center of an earthquake. Please don’t take this as me trying to shoot your idea down, though. It’s a good idea, and if it weren’t for ideas like this, the world would not have innovated much at all.

[@aryanverma2926]

Is there an online simulator available for this experiment?

[@yatogami7393]

Better than changing the polarity inside one of the speaker 😅

[@surajdubey3496]

Why we always use same frequency?

[@achmadrizal34]

Is moving the microphone (from the center of the distance of two speakers) to half lambda away, will always create fully destructive interference? I am considering that although the crest meets the trough, but the number of the amplitude at that time is different.

[@gabbardaku]

Achmad Rizal Yo need a coherent source for that which is not possible to create in normal circumstances

[@thecrazygamer7334]

@@gabbardaku but we can create coharent source of light right?

[@joemomumbo]

@@thecrazygamer7334 that is a monochromatic laser

[@kokospice2516]

Why don't you move microphone up and down?

[@physicsdemos]

I could certainly move the microphone up and down, but it would not show the interference effect. To hear this effect, you need to change the difference L2-L1 between the path length L1 from the microphone to one speaker and the path length L2 from the microphone to the other speaker. If you held the microphone equidistant from the two speakers, you could move it up and down all you want and it wouldn't change L2-L1, because L1 would always equal L2 and L2-L1=0. Moving the microphone sideways allows you to change L2-L1 to see the interference effect. For more information, see kzbin.info/www/bejne/pYiyhKWil9aJgNE.

[@jupitersaturnuranusneptune2816]

But nowhere does it go to zero (no sound).

[@Jbird1978Qqqqqq]

Is this dude awake

[@saanvi652]

❤️❤️❤️🔥🔥🙏🙏

[@lovishmonga1378]

Why did not the amplitude become zero on destructive interfernace

[@milikumari5474]

Coz its theoretically true but in reality various other factors come in play

[@hydrochloricacid2146]

in practice there are a few other things to consider: - you have harmonic distortion at the source and speaker level: you simply aren't producing a pure sine wave. The idea that you get an interference pattern with "zero-ed out" points where you get total destructive interference can only really happen if you have a single frequency. You effectively have multiple overlapping interference patterns which don't line up between each other. -you have other external sound sources. The person moving the microphone around produces some amount of noise, even while trying to be as silent as possible. This is picked up. -you get reflection against the room's wall. These fade quickly but act as additional sound sources. -Even with a pure sine wave and no external noise, you still only get that total destructive interference in infinitesimally-small locations where the sound waves precisely cancel out. It's possible to approximate this over a relatively small fraction of the incoming wavelength, but the reality is that the type of microphone used here is actually a relatively large fraction of the sound's wavelength (which is 17cm at 2kHz whereas a microphone of this type has a membrane a few millimeters across.

[@prashantkiran6869]

How do we ensure there’s no initial phase difference between the sources?

[@chaitanyagaur7674]

Same question. I think that the same source is working on both speakers, so initial phase difference is zero. If these were two random speakers of some DJ, then there would have been no interference pattern.

[@hydrochloricacid2146]

both speakers are powered by the same sine source, so it's reasonable to expect both sounds to be in sync. In practice, even a slight shift in phase will just result in a slight spatial shift in the interference pattern the microphone picks up one, which is likely to be far smaller than whatever uncertainty you have regarding distance.

[@seeunkang2806]

result 3:00

[@matheusestudos]

2022-09-23

[@rahuldwivedi1070]

Well why in this demo aren't the interference pattern detected gets disturbed by Sound waves bouncing of the walls?

[@nathanielholmes79]

asmr

[@TheCardboardkey]

There is a mistake here. Please watch this video: kzbin.info/www/bejne/pnvMoJuvrqd9q5Y

[@tilliemargulies8501]

hello orelia i hope u ACTUALLY look at the comments this time. if not i'll be disappointed

[@orelianewman9104]

ew no who would bother to scroll down this far

[@orelianewman9104]

what a dork

[@tilliemargulies8501]

@@orelianewman9104 u

[@shreyashpawar324]

is there likes glitch man

[@tilliemargulies8501]

all these ppl commenting are such nerds... is that mean?

[@orelianewman9104]

omg tillie my favorite nerd

[@tilliemargulies8501]

@@orelianewman9104 ur a nerd moob

[@urdad6673]

Doesnt he look like Micheal scott?

[@tilliemargulies8501]

hi leilah how r u?

[@orelianewman9104]

hi leilah i dont think i know u but u have a pretty name