Don't mind her, Ooyodo, being over 20 makes you hear less stuff. Doesn't mean you are old. There are rare cases where people over 20 hear stuff just like a kid can though.

Aren't those supposed to be ultrasonic anyway? Not much point behind an sonic animal repeller if it also drives you crazy with the noise.

NNescio said:

Aren't those supposed to be ultrasonic anyway? Not much point behind an sonic animal repeller if it also drives you crazy with the noise.

Not every of those frequencies drives you crazy while still have enough effect on mosquitoes. And I bet you know that.