Ocean waves make water rush up and back with each wave. Radio waves make electricity flow up and down in the antenna wire like that. Radio wave electricity flows back and forth about a million times each second. It changes back and forth faster for a shorter distance between the waves. The detector changes the radio wave electricity into sound electricity.
Radio stations make the radio waves get stronger and weaker as the sound changes.
The strength of the radio waves copy the sound vibrations. The detector changes the back and forth radio wave electricity into one way sound electricity. When the radio wave is strong, it makes strong sound electricity. When the radio wave is weak, it makes weak sound electricity. This makes sound electricity that copies the sound vibrations.