Cessna 150/152/172 stall warning "horn" works by negative pressure. https://www.youtube.com/watch?v=Q1JRTCBkWKQ https://www.youtube.com/watch?v=Q1JRTCBkWKQ And

Cessna 150/152/172 stall warning "horn" works by negative pressure. https://www.youtube.com/watch?v=Q1JRTCBkWKQ https://www.youtube.com/watch?v=Q1JRTCBkWKQ And then the Cessna 182 has an aerodynamic switch that activates an electric "horn". And in either case they can get jammed up with bugs. But we do a lot of training with slow flight, approach to stall, full stall, and recoveries including recovery from the ensuing dive and secondary stalls.