Most cities have noise ordinances so you won’t want the audio for your projection to be too loud. One solution to this is to broadcast an FM signal so that people can listen to the audio on their FM radios in their cars. This one will cover an area that will allow your viewers to tune in up to several houses away from yours. Very easy to use with dials to adjust input levels and buttons to select the station you want to use. Very reasonably priced as well.
Signstek 7W 7C FM Transmitter Mini Radio Stereo Station PLL LCD with AntennaFashion Black