Humans can hear sounds approximately within the frequencies of 20 Hz and 20,000 Hz. Anything below 20 Hz, typically cannot be heard although it can be felt. This can be experienced to when you feel the bass of a song. Likewise humans normally cannot hear any sounds above the frequency of 20,000 Hz. Although human hearing is limited to this frequency range, many animals have a wider range of sounds of which they can hear, like dogs for example.
The frequency range of dog hearing is approximately 40 Hz to 60,000 Hz, of course depending on the breed of dog as well as its age. Like humans, dogs can begin to go deaf as they become older. In some breeds of dogs it is natural for them to go completely deaf in their old age.