The device needs to stream and power a Laser beam that is focused to more than 1 Km of Distance from within a window, Voices and sound area absorbed by the window and transmitted onto the laser beam called "modulation". The receiver (at the other end of the beam) needs to demodulates, process and amplify the signal, the result a good quality audio.
This audio files needs to be stored within the Microcomputer you should chose for the project, the software needs to be able to analize the audio data, cut the parts where theres no audio or the fog and other ambiance factors may low the quality of the listening feed, process and order them, for then upload the data into a specific server the audio material for the presentation of the information.
Several knowledge about Lasers and Optics should be require to complete this project. Chosing digital materials to interact with Microcomputer will be crucial elements that will be evaluated for building this device. We haven't make the test for chosing the options if an analogous signal will deliver the same quality of a digital laser with a micro controller, or some function that allows obtain a proper quality than analogous.
A Rugged enclosure should be designed for protecting the device from Rain and other weather eventualities. The enclosure needs several materials, 3D Printing gives us the opportunity of have little inventory, without investing too much in the development of plastic moulds that will be expensive and maybe and will be requiring longer times for production.
A solar antenna should be designed and placed that needs to be able to fold and saved again for installing the device outside buildings and in Outdoors for a better reception of Laser beam and 4G Wireless data.
A tripod Camera style thread beneath the enclosure should be designed for providing the device the ability to be fixed in a tripod or other kind of mount that can be custom designed for the application but universally adaptable to the device.
Adafruit devices, Raspberry PI, CHIP, and other microcomputers can be used for the project, if you have an idea to make a smaller and a Custom PCB that includes somehow 4G Communication, your opinion is accepted, the best we could integrate in an homogenous device the best.