In the ear, the structure that can keep the pressure balance inside and outside the eardrum is _ _ _ _ _ _ _, and the structure that can feel the sound wave information is _ _ _ _ _ _.

① The structure connecting middle ear and pharynx is eustachian tube. When swallowing or chewing food, the nozzle is opened and air enters the tympanic cavity, so the air pressure in the tympanic cavity can be adjusted to maintain the air pressure balance inside and outside the tympanic membrane, thus maintaining normal hearing.

② The auricle has the function of collecting sound waves, and the external auditory canal transmits sound waves to the tympanic membrane, which converts sound waves into mechanical vibrations. The ossicles amplify the vibration of the eardrum and transmit it to the inner ear. The semicircular canal and vestibule have position (balance) receptors, and the cochlea has auditory receptors, which feel the stimulation of vibration and produce nerve impulses.

So, the answer is: eustachian tube; cochlea