I read this information off a website:

"The most important requirement for interference is to have at least two waves. One wave alone behaves just as we have been discussing. We shall see that there are many ways to create a pair of waves to demonstrate interference. The simplest way to create two sound waves is to use two speakers. If we place them side-by-side, point them in the same direction and play the same frequency, we have just the situation described above to produce constructive interference:If we stand in front of the two speakers, we will hear a tone louder than the individual speakers would produce. The two waves are in phase. Now imagine that we start moving on of the speakers back:At some point, the two waves will be out of phase – that is, the peaks of one line up with the valleys of the other creating the conditions for destructive interference. If we stand in front of the speakers right now, we will not hear anything! This must be experienced to really appreciate. Equally as strange, if you now block one speaker, the destructive interference goes away and you hear the unblocked speaker. In other words, the sound gets louder as you block one speaker!How far back must we move the speaker to go from constructive to destructive interference? We know that the distance between peaks in a wave is equal to the wavelength. If we look back at the first two figures in this section, we see that the waves are shifted by half of a wavelength. So, in the example with the speakers, we must move the speaker back by one half of a wavelength.What happens if we keep moving the speaker back? At some point the peaks of the two waves will again line up:"

I found this very interesting.How can I practically do this experiment? I've never experienced anything of the sort with my speakers before.Sounds very strange and I would like to practically do it.How would I begin to do this and for the destructive interference, where would I need to stand infront of the speakers? In the middle of the space between the speakers or towards one of them, and for it to work should I walk towards the speakers or slowly walk away from the speakers in order to experience destructive interference, I would very much like the idea of increasing the volumes of my speakers to 100% and hear absolutely nothing. So, how would I do this and what distance do I need to move the speakers back. Here's the website : http://www.phys.uconn.edu/~gibson/Notes/Section5_2/Sec5_2.htm


1 Answer 1


I have never done it myself, but it can work given that in air the wavelength of sound is between few tens of mm to tens of meters. choose a pure sinusoidal tone with about 1m wavelength, put the speakers about the same distance pointing the same directions. Maybe better to use one ear only? Or a microphone to record.

Unrelated, but cool: When you are done with that, think about beating between 2 slightly different wavelength, and check the binaural beat https://en.m.wikipedia.org/wiki/Binaural_beat


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