The organs of hearing in dogs
Like humans and other animals, dogs perceive sounds using their ears which are actually composed of 3 parts:
- The outer ear
The outer ear channels sound towards the middle ear. This is the "tip" of the iceberg, in other words the visible part of the dog's ear. It is mainly composed of the auricle, or auricular pavilion, and the external auditory canal.
In dogs, depending on the breed, the pinna of the ear can have very different morphologies.
We meet like this:
- dogs with short erect ears like those of the German Shepherd or the Siberian Husky,
- dogs with semi-drop ears like the Schnauzer or the Fox Terrier,
- dogs with long, droopy ears like those of the Beagle or the Cavalier King Charles.
The auricular pavilions of dogs have the particularity of being equipped with many muscles, which allows the dog to orient them according to the source of the perceived noise and, thus, to better localize the sounds.
But, thanks to their mobility, dogs' auricular pavilions also play a major role in intra-specific visual communication. Dogs express many of their emotions through the movements and position of their ears.
- The middle ear
The middle ear is a cavity located in the temporal bone.
On the side of the outer ear, it is bounded by the eardrum, the membrane that transmits sound vibrations to the chain of 3 ossicles contained in the middle ear. And on the inner ear side, it is closed by the oval window and the round window.
- The inner ear
The inner ear is made up of the vestibular system, which intervenes in the sense of balance, and the cochlear system, responsible for transforming the mechanical waves of sound into nerve impulses that can be transmitted to the central nervous system via the pathways. auditory. Only the latter therefore intervenes in the direction of the dog's hearing.
The peculiarities of dog hearing
The hearing function of the dog is a very important function for the dog because it allows him in particular:
- to detect danger or prey in the case of hunting dogs by the noise he or she produces before being perceived by the visual or olfactory system,
- to pick up the auditory signals emitted by congeners (vocalizations, moans, barks) or humans and to enter into communication with them.
The dog is completely deaf in the first 15 days of its life, but then it becomes able to perceive sounds in a much wider frequency range than that of humans.
It perceives low frequency sounds, from 15Hz and high frequency sounds (or ultrasound) up to 60,000 Hz. For comparison, our human ear only perceives sounds up to 20,000 Hz maximum.
The dog's fine hearing would also allow him to hear sounds coming from a distance 4 times greater than that where we can hear them.
Hearing disorders in dogs
Dogs can suffer from deafness just like humans.
It can settle gradually with age. It is not uncommon for older dogs to become deaf. Most of the time, this is due to a small stroke that has no other he alth consequences for the dog.
Deafness in dogs can also be congenital and affect very young dogs. It is estimated that nearly 90 dog breeds are thus predisposed to congenital deafness. Among the most impacted breeds, we can mention the Dalmatian and the white bull terrier. The risk of deafness is also greater in so-called "double merle" dogs and especially in Australian Shepherds.