Compact Unidirectional Audio Speaker

[1MK5]

Hi everyone,

I am posting this thread just to find some information.

I have a science project which try to make a compact directional sound for detecting movement.

Now, the electronics which my group is developing is on a small PCB board (approximately 5x5 cm)

I am wondering if there are anyone here could suggest if there is a commercial compact (small) unidirectional speaker which I can mount on the PCB?

I have tried a Google search: Directional Speaker, or Unidirectional Audio speaker; and it gives me a list of large-size directional audio speaker for home or office applications.

Finally, I'd like to thanks in advance to everyone in the forum.

Cheers,

1MK5

 

[maimonides]

Directivity in a speaker is dependent on the ratio of wavelenth to diameter.
Your speaker (or speaker array) will have to be at least as big as the wavelength to get reasonable directionality. Your best bet might be using four small ultrasound transducers in the corners of the PCB and making the frequency as high as practicable. (Attenuation)
You´ll find links to theory here: http://en.wikipedia.org/wiki/Directional_Sound