fun with soundwaves

[iamallthings]

today in school, i learned the formula to determine the frequency of the lowest standing wave in any given space.

if you play the corresponding frequency as an audio test tone out of your speakers (the louder, the more fun),
you can then walk around the room, and with any change in position within the room (left, right, up down, forward, backward),
the way you perceive the tone changes drastically, from the loudest amplitude of the signal you are playing to near silence,
within a mere couple of feet from one another. it is tripped the fuck out, indeed.



it feels like you're controlling the volume of your system with the motion of your head, but really you're moving your ears
into and out of areas of the room where the sound wave for your test frequency has reflected off of another surface and
is returning as the mirror image of itself, cancelling out the sound where it is most similar.

try it yourself! here's the formula: λ = V/l

where:
V = 1,130ft/sec (in a room with a temperature of 70 degrees F. if your temp is higher, increase V by 1.1ft/sec in the equation)
l = length of the room in the direction the speaker is facing
λ = will be your test tone frequency, expressed in Hz

for example, my room measured at 18ft in length, my current temp is 75 degrees F, so:
V = 1,135.5
l = 18
λ = 1135.5/18
63.08 = 1135.5/18
λ = 63.08Hz

[RandoRando]

ive always noticed this playing test tones, it is weird, is it the walls reflecting that were hearing change, or is it all the grooves in our ears changing the sound thats going into our canal or whatever, cause even if you were outside this happens, and where in the desert are you located?

[iamallthings]

ive always noticed this playing test tones, it is weird, is it the walls reflecting that were hearing change, or is it all the grooves in our ears changing the sound thats going into our canal or whatever, cause even if you were outside this happens, and where in the desert are you located?

when a wave doubles back over itself, due to reflection/refraction it cancels itself out anywhere that the polarity of the two waves are in opposite. for instance, if you were standing in a location where the amplitudes of the two opposing waves were 30Hz and -30Hz, the resulting frequency at that point would be 0hz.

if you are outside in an open area without trees or people or anything that would be reflecting that sound wave, you may be experiencing some manner of phase shift in your stereo channels, which demonstrates another example of the same principle, but the cause is different.

[makemerich]

sound like a conservatory student.

[iamallthings]

sound like a conservatory student.

yes

[3za]

That looks like a sine wave threesome to me...

[spectrum1]

i stared at that picture for like 5 minutes

[Turnipish_Thoughts]

i stared at that picture for like 5 minutes

lol so did I. Me and my mate just had a random conversation off the back off this picture about all sound waves in nature (as in non digitally created ones) are basically interacting standing sine waves of varying frequencies. cool pic.