Final answer:
The myelination of neurons related to hearing starts in the fetal stage, after initial neural development in the embryonic stage. It involves the formation of an insulating sheath around neurons for efficient impulse transmission.
Step-by-step explanation:
The myelination of neurons involved in the sense of hearing begins during the fetal stage of development. Specifically, the auditory nerve and the middle ear undergo development that allows the fetus to hear. The neural tube, which eventually becomes the spinal cord and brain, starts forming during the embryonic stage through neurulation, which happens around the third to the fourth week after fertilization. However, the comprehensive development of auditory pathways, including myelination, continues into the fetal stage. This stage involves considerable development of vital organs and systems, and by this time, the fetus is able to hear both internal and external sounds.
During the fetal stage, organs such as the brain and spinal cord continue to mature, with myelination playing a critical role in the proper functioning of the nervous system. Myelination provides the insulating sheath around neurons that is essential for fast and efficient transmission of neural impulses. These processes of neural development, including myelination, occur after the foundational structures have been established during the embryonic stage.