Final answer:
The large air-filled openings of the auditory tube in horses are known as the auditory tube's pharyngeal orifices or openings.
Step-by-step explanation:
In the horse, the large air-filled openings of the auditory tube are known as the auditory tube's pharyngeal orifices or openings. These openings play a critical role in the equalization of air pressure between the middle ear and the nasopharynx, ensuring that the tympanic membrane, or eardrum, can vibrate freely to transmit sound efficiently to the ossicles within the middle ear. The ossicles, which consist of the malleus, incus, and stapes, further amplify sound and transmit it to the inner ear where it is converted into neural signals for the brain to interpret.