With which the birds sing. A bird's voice device.
Birds sing beautifully and each bird has its own specific singing. Birds that can't sing at all, there are practically no birds in nature.
Of course, there are exceptions, such as ravens, they do not sing, they shout, it is their kind of communication with the world, but mostly birds, of course, sing.
It should be taken into account that regardless of whether a bird sings or expresses its attitude to the world in some other way - the voice system of all birds is the same.
What about the birds' voice system?
The bird's voice box, like that of a human, refers to wind instruments because it is designed in such a way that the sound is generated by the movement of air from the lungs.
The sound wave emitted by the bird when singing or other manifestations of voice are formed by a jet of air that affects the eardrums.
The vocal cords located in the larynx produce sounds whose strength and frequency depend on the tension of the vocal cords.
Birds have two larynxes: one upper and one lower.
It is the presence of the lower larynx distinguishes the device voice of birds, because of a very complex device, the presence of the lower larynx allows birds to make specific, nothing like the sounds.
By having two sound vibrators in the lower larynx, one and the same bird can produce different, different voices.
In addition to a complicated voice system, birds have another ability: by applying the movements of their torso and muscles, birds can change the device of their voice system, which allows them to control and manage their voice.