Microphones Shotgun speaker? (opposite of shotgun microphone)

oh wow cool! but even though this is the idea, i was thinking of something much smaller egronomically, something maybe using Huygens–Fresnel principle though that would be impossible since the sound is not a laser of a single frequency, and with fringes you could direct the light, making external waves cancel each other only allowing the light in one direction - straight, THOUGH after looking at how light waves behave I am now thinking, with sound, to cancel external waves it would probably need 4 directional speakers, 3 of which would be cancelling the external waves, and one in the middle would be least affected sounds really complicated, i think other than speakers it would need some echo engineering thing calculated in autocad and lots of physics, god danm it
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The polar plots of shotgun mics show that the directional behavior changes quite radically with the frequency, and they have lots of minor lobes out the sides and rear. That would tend to make a "shotgun speaker" fairly ineffective at focusing the audio just in one direction. It would work fairly well at high frequencies but work progressively worse at lower frequencies. That's why the example above is a parabolic instead of an interference tube. To make it work most effectively, the tube would have to be very long, just as there are short and long shotgun mics.
 
wow this is making more sense now, what you see in the picture actually generates high frequency sound, a water droplet (think water droplet in the cave with echo, only without echo, but that high pitched *drip*)
I have been trying to find what they used, but absolutely no success

and speaking of all the minor lobes on the sides, maybe those lobes were engineered for directionality

anyway so i take, if the sound consists of higher frequencies it should add to directionality?

goal is to confuse the target, they cant know where the sound is coming from, now i remember from highschool days we had this ultrasound in our phones, nobody would know where the sound was coming from but it was insanely annoying, base however you can locate right away.
 
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It isn't actually the tube that makes a typical modern shotgun microphone microphone directional, it's the openings in it and how the sound through those openings interacts with one another and the direct sound at the diaphragm, thus the 'interference tube' reference FMEng used. Sounds from different paths that arrive in phase are summed, sounds that arrive 180 degrees out of phase are canceled and those in between are, well, somewhere in between. Since wavelengths, and thus relative phase for a given distance, vary with frequency the results of a fixed interference tube also vary with frequency, thus the lobes and nulls. It also means that getting an interference tube to be effective at lower frequencies requires a very large tube.

For speakers a Bessel array, essentially a two dimensional array of speakers, is a much more realistic method of obtaining a more controlled and electronically variable interaction in two axes, but lobing, etc. are still relevant.

What surprises many people is that many 'modern' audio concepts were actually conceived from 50 to 100 years ago by some of the early audio industry greats, it is just now that the technology is allowing the concepts they developed then to be practically implemented. For example, many seem to be enamored with newfangled line arrays, not realizing that the general concept goes back to around 1940 and that 'columnar' arrays were popular in the 1950's. It's just that today's technology allows for new approaches to and implementation of those earlier concepts.
 
A while ago I read about the concept of a sound "laser" that would produce very narrow beams of audio for the purpose of kiosk advertising. The idea being that as people walk through a defined area they hear the ad but other people don't, keeping noise pollution down. The concept is similar to AM radio with audible sound riding on a "carrier" of ultrasound. Only higher frequency audio was possible and I'm not sure how much range it had.
 

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