This may seem to fit more properly into "news of the weird" than social science research, but stick with me for a moment.
The news aggregator Ananova is reporting on The Mosquito (also known as the Sonic Teenager Deterrent), which is allegedly capable of producing an annoying, 80-decibel sound that only teenagers can hear. Apparently, as we enter adulthood, we gradually lose our ability to hear tones in that range. The device was supposedly invented by a UK shopkeeper, annoyed at the teens malingering near his shop.
Once you stop chuckling, try imagining it was possible to develop other technologies capable of causing discomfort to other social groups, based on gender, ethnicity, etc. Sound trucks are one thing, but what are the implications of creating targeted "public nuisances"?