Every physical obstacle – especially for hunting predators – hinders visual communication. This is why hearing is very important and very refined. It is most developed sense after sense of smell in almost all canids.
Human ear can detect sound frequencies from 20 Hz to 20,000 Hz. Dogs detect sounds lower than 16 Hz and above 100,000 Hz. So, regarding lower sounds humans do not lag behind much, but regarding higher notes dogs are way ahead. This is why they can catch mice and other rodents in the dark since they can hear tiniest squeaky signals with ease which, for human hearing, is unobtainable.
They can hear from far away. Except that, in most canids ears are very mobile which enables precise positioning of the sound source. This is why wolf can hear and determine the place of cracking twigs from 3 km away. On the other hand, dogs in the wild that hunt at night have the best hearing and that is why it is thought that foxes have better sense of sound than wolves.
Domestic dogs with folded ears most commonly have noticeable difference between senses of sound and smell. This type of ears is less mobile and close the air flow to ear canals but their sense of smell is impeccable. Anyhow, there are no strict norms.
