# Directional Speakers

I am working on an exhibition where I want to use DIY, self-made directional speakers for transmitting interviews to the visitors.

Until now I have seen a couple of video on Youtube like the one listed bellow

Diy video of the directional speaker

This exhibition in Berlin seems to have used some type of directional speaker but I am yet unsure what exactly they have used. Link.

My question is as follows: What would be the best solution to include some directional speakers in my exhibition?

In case I build the diy model, from the video, will the voice from the interview be clear enough for the visitors to understand.

• Those Youtube vids sound like cr*p. I would avoid. Novel and clever concept, but that's not the sound you're going for. Doing it w/o computers needs speakers that are very far apart. What you're seeing in Berlin is possibly a much more advanced concept that makes use of sophisticated algorithms (i.e. not just a couple speakers). I researched this a couple years ago for an exhibit, just like you. I found these guys: browninnovations.com/directional-speakers-home Didn't build the exhibit, but I'd have dropped the  and bought into theirs if we had. – Kyle B Jun 10 at 20:57
• @KyleB B, thank you for your comment. In regards to the quality of the DIY concepts, as long as the voice is understandable ( meaning even if it is a bit shaky) it would do the job for the exhibition, considering that the art/genre of the exhibition is Time. I don't have a big budget. Any other advice you could give would be more than appreciated – Ed1995 Jun 10 at 22:19
• @Ed1995 it simply doesn't work, not even for speech. Audio inherently spans multiple decades – beamforming that requires relatively complicated logic. "Wavefield synthesis" is the term you want to google. The thing that youtube video shows is just a not-even-phased array of far too small speakers, which has the typical sinc-shaped side lobes, with spacing defined by the ratio of array diameter to wavelength. Now, speech has wavelengths varying from 10 cm to ca 6m – you can imagine how well that works. Yes. In a single point straight in front of the array it works. – Marcus Müller Jun 10 at 22:30
• but you get strangely-sounding sidelobes all over the place, and since human hearing is really quite sensitive, the first sidelobe with only -13 dB less power than the main direction is not that less loud. Not to mention that room acoustics will make you hate the fact that reflections exist and can form high-amplitude constructive interference in the funniest places :) – Marcus Müller Jun 10 at 22:34
• Quickest, cheapest and easiest method would be to stick your speaker inside a parabola. No fancy software or circuitry required. Won't be nearly so effective as beam forming but you can't beat the simplicity and cost! You would put your speaker at the parabolas focus (yes...math!) aimed backwards. Parabola would need to be kinda big and deep... A direct TV dish is too shallow. Something like this: instructables.com/id/Build-a-Parabolic-Speaker Lots of DIY's for this on the net – Kyle B Jun 11 at 3:27