Turtles have a pair of inner ear that has a typical structure. The structures of the middle ear perform the function of amplification of sound waves and their bringing to the inner ear. The cavity of the middle ear is externally bounded from the external environment by the tympanic membrane (tympanic membrane). This membrane in most species of turtles is covered from the outside with a horny shield.
The shield can be very dense, and in this case the turtles are able to hear sounds only in the low range, on the order of 150-600 Hz. Low frequencies include knocking, steps, clapping, rustling, car noise, etc. In sea turtles, the auditory canal is closed strongly with thickened skin.
To determine the presence of hearing in turtles, electrophysiological studies were carried out, that is, recording the electrical activity of the auditory nerves upon exposure to sound. These experiments showed that turtles can hear low sounds up to 500-1000 Hz. This is evidenced by the electrical impulses of their auditory nerves and centers. In aquatic turtles, hearing is almost as sensitive as in cats. Turtles well feel the vibrations of the soil. A person can call himself a turtle with the help of sounds. Also, turtles hear the vibrations of the floor, while vibrations through the legs and carapace are transmitted to the inner ear.
Thus, the forest tortoise (Clemmys insculpta) well perceives low-frequency sounds of the order of 500 hertz, but if the frequency is increased, the hearing ability of the turtle quickly decreases. Apparently, sounds do not play a leading role in the life of turtles, except during the mating season, when some species (especially land ones) even roar.