Final answer:
The external acoustic meatus is also known as the a. auditory canal, a part of the external ear responsible for leading sound waves toward the eardrum.
Step-by-step explanation:
The external acoustic meatus is also known as the auditory canal. This is a tube-shaped structure that is part of the external ear and leads sound waves inward towards the tympanic membrane, better known as the eardrum. The auditory canal is the large opening on the lateral side of the skull and is responsible for transmitting sound from the external environment to the middle ear. It is important not to confuse the auditory canal with other parts of the ear, such as the Eustachian tube (pharyngotympanic tube), which connects the middle ear to the pharynx and helps equilibrate air pressure across the tympanic membrane.
The external ear consists of the auricle (pinna), the auditory canal, and the tympanic membrane. When sound waves enter the auditory canal, they cause the tympanum to vibrate, initiating the hearing process. Therefore, the correct answer to the question 'Which is also known as the external acoustic meatus?' is a. Auditory canal.