what I just sent to my physics professor (Warning; it has to do with sound waves and...science.)

"The goal of this is to find out the wavelength of one sound-wave with a fairly high accuracy by using a combination of a wave of a known wavelength and the unknown wave. From my experience, sound waves which are very close to each other in frequency and which are sounding at the same time end up creating a third pulsating noise. This pulsating noise is due to the additive property of the waves (when waves “sync up” with each other, they add to each other and increase in amplitude). Using the time of the period of the addition of the unknown wave and the known wave, one can find the wavelength of the unknown wave to some accuracy.

Vs=Speed of sound
λ1= Wavelength of the known wave
λ2= Wavelength of the unknown wave
t1+2= Period of combination of λ1 and λ2
W1= Known wave
W2= Unknown wave

First, find how many cycles of W1 happen in t1+2
(Vs)(t1+2)/( λ1)=Cycles of W1 per period of t1+2
Now, we know that (if W2 is slightly smaller thanW1) the unknown wave will be x meters smaller than the known wave. Therefore, we know that (x)(the number of cycles in wave W1 over t1+2)=(wavelength of the known wave). Therefore, (Wavelength of the known wave)/(number of cycles in wave W1 over t1+2)=x
(λ1)/[((Vs)(t1+2))/ (λ1)]
Which is equivalent to
λ12/[(Vs)(t1+2)]

This gives us the “x”, the difference between the λ of the known wave and the unknown wave. Both waves will interact the same if they are x meters larger or x meters smaller than the known wave.

(λ2) ±(λ12)/[(Vs)(t1+2)] "

So I am a loser...