Two ripple-tracks, one for each tire, should give stereo sound. Two tires each makes it all echo-y. Take it to a mainstream researcher, but don't let them look at it in detail. A large, hollow-ended cylinder is attached to a bass loudspeaker. The open end of the cylinder is covered with a flat plate, and a 3in.
Pulses can be repetitive, so a continuous beam of vortices is projected.
Pulse waveform can be tailored to produce robust, fast, silent vortices. Each vortex incorporates air from within the cylinder, and carries this air along as it travels. If a sharp point is attached to the dome of a VandeGraaff generator, the point will spew charged wind. If you stand in this air stream, it will charged your clothing and hair, which will start clinging to your body. The projector shoots gas pulses which cause occasional loud and unexplained explosions within the device.