Canada's Union Hearing Aid Centre has been doing a good job with its surprising, self-targeting ads. In a campaign last year, they had melodious piano music accompanying the most annoying, high-frequency sound ever -- but you could only hear it if you had good hearing. Now, the company and DraftFCB Toronto are back, with a print poster in Toronto's West End that emits that same sound when you walk by. The poster features copy that purports to test your eyesight, with the font getting smaller on each line. At the end, the tiny font says that if you got that far, you might have perfect eyesight, but really bad hearing -- since they couldn't hear ad's semi-sonic frequency. A television spot does a similar thing, by getting people to test their hearing by pretending to test their eyes, instead.