Works too well

Looking for a cheap, simple baby monitor (to date still without success) we bought us this baby monitor. I'll still return today. It's a disaster - as soon as a truck or the tram (soundproof windows were closed) drove past it was with a cheerful noise to. (I live in Berlin - so every minute.) There is no function at the transmitter shut enforce the sensitivity. My baby sleeps with my son in a large room and even his bruxism has transmitted it. It works as it were too good. So who makes every fart or toes wiggle the baby in his sleep is interesting, for which the device is very good. ;)